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iOS 26: Underexposed image in exposure bracket appears clamped vs single capture
Hello, I have an iOS camera app that captures exposure brackets and performs custom HDR processing. On iOS 26, I’m observing a visual difference between: a single photo captured at –2 EV, and the –2 EV frame from an exposure bracket (–2 / 0 / +2 EV). On iOS 26: The single –2 EV image looks natural and consistent. The –2 EV image from the bracket appears clamped / distorted, most noticeably in high dynamic range scenes (highlight compression and loss of detail). On iOS 18, both approaches produce visually identical and correct –2 EV images. The issue only appears for bracketed captures on iOS 26. Attachments (examples) iOS 26 Single capture –2 EV (JPEG): /Users/danilobudimir/Downloads/ios26SingleImage/JPEG image-4006-8B77-51-0.jpeg Single capture –2 EV — Capture report (dumped settings): /Users/danilobudimir/Downloads/ios26SingleImage/UnderExposureDebug_CaptureReport_2026-01-09T15-59-20Z.md Bracket capture –2 EV frame (JPEG): /Users/danilobudimir/Downloads/bracket_iOS26/JPEG image-45CE-9793-A5-0.jpeg Bracket capture — Capture report (dumped settings): /Users/danilobudimir/Downloads/bracket_iOS26/UnderExposureDebug_CaptureReport_2026-01-09T15-55-42Z.md iOS 18 Single capture –2 EV (JPEG): /Users/danilobudimir/Downloads/ios18SingleImage/JPEG image-47FD-AF73-28-0.jpeg Single capture –2 EV — Capture report: /Users/danilobudimir/Downloads/ios18SingleImage/UnderExposureDebug_CaptureReport_2026-01-09T16-25-27Z.md Bracket capture — –2 EV frame (JPEG): /Users/danilobudimir/Downloads/bracket_iOS18/JPEG image-4A4C-9E93-46-0.jpeg Bracket capture — Capture report: /Users/danilobudimir/Downloads/bracket_iOS18/UnderExposureDebug_CaptureReport_2026-01-09T16-27-23Z.md Question Is there any new behavior in iOS 26 AVFoundation related to: AVCapturePhotoBracketSettings, tone mapping / HDR preprocessing, or internal image processing applied specifically to bracketed frames? Is there a new flag, format requirement or opt-out mechanism required to preserve linear underexposed frames in exposure brackets?
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855
Jan ’26
AirPlay v1 is broken in iOS 18.4?
After upgrading to iOS 18.4, I'm no longer able to establish an AirPlay v1 connection to an audio system. The symptom is that the AirPlay route picker just spins when trying to connect to an audio system. It eventually gives up. I tested this on an iPhone 14, connecting to a HomePod, AirPort express, AppleTV and a Wiim Pro. If I try connecting with AirPlay v2, ex: using Apple Music, the connection succeeds and audio can be played. I'm the developer of an app that plays audio over AirPlay while also recording. My app has to use AirPlay v1 because AvAudioSession doesn't allow the policy .longFormAudio when the category is .playAndRecord. This issue is a real pain as it means my app is suddenly broken for many thousands of users. Is anyone else seeing this issue? Any suggestions for a workaround?
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527
Jun ’25
dlsym cannot find symbol g_dwILResult when debugging an audio plugin
I am trying to debug the AAX version of my plugin (MIDI effect) on Pro Tools, but I am getting the following error (Mac console) when attempting to load it: dlsym cannot find symbol g_dwILResult in CFBundle etc.. I used Xcode 16.4 to build the plugin. Has anybody come across the same or a similar message? Best, Achillefs Axart Labs
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565
Sep ’25
CoreMediaErrorDomain -12888: Bandwidth down-stepping when using 2sec segment duration
the problem is when using HLS live stream with AVPlayer on iOS/ tvOS the player chooses first highest bandwidth then slowly steps down to lowest (within 1-3min) and eventually steps up again then repeats to step down. the AVPlayer error log sends events: errorStatusCode: -12888, errorDomain: Optional("CoreMediaErrorDomain"), errorComment: Optional("The operation couldn't be completed. (CoreMediaErrorDomain error -12888 - Playlist File unchanged for longer than 1.5 * target duration we use standard segments in CMAF format, 2sec duration #EXTM3U #EXT-X-VERSION:6 #EXT-X-TARGETDURATION:2 #EXT-X-MEDIA-SEQUENCE:147065903 #EXT-X-MAP:URI="video_1_4660000_init.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2" #EXT-X-PROGRAM-DATE-TIME:2025-04-30T12:51:07 #EXTINF:2.000, video_1_4660000_t17460174670001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 #EXTINF:2.000, video_1_4660000_t17460174690001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 #EXTINF:2.000, video_1_4660000_t17460174710001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 when using 6sec segments the player stays stable at highest bandwidth. is there a way to avoid this error? in AVPlayer or HLS configuration?
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390
May ’25
Logged error/warning in FigCaptureSourceRemote when capturing a photo
I'm using this library: https://github.com/Yummypets/YPImagePicker to capture photos. I've modified it slightly, and I'm using an older version. When testing on my iPhone 16e, ios 26, whenever I take a photo, I get the following two error messages: <<<< FigXPCUtilities >>>> signalled err=-17281 at <>:302 <<<< FigCaptureSourceRemote >>>> Fig assert: "err == 0 " at bail (FigCaptureSourceRemote.m:569) - (err=-17281) These error messages appear, but as far as I can tell, the photo comes through OK, and I can save the data no problem. I've even removed all my handling code to see if it was something I was doing. I don't really want to ship with these errors showing, but I also have no idea what can be causing this error to appear. chatgpt was not helpful diagnosing this. Does anyone know what can cause this error Is there a way I can see the source code to figure out if there's something I'm doing wrong here? It really seems like this is an internal apple error, or else I would have expected more details on the error relating to the code I've written. Any clues would be appreciated!
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782
Dec ’25
builtInLiDARDepthCamera doesn't work on the 2020 iPad Pro on iOS 26
On iOS 26.1, this throws on the 2020 iPad Pro (4th gen) but works fine on an M4 iPad Pro or iPhone 15 Pro: guard let device = AVCaptureDevice.default(.builtInLiDARDepthCamera, for: .video, position: .back) else { throw ConfigurationError.lidarDeviceUnavailable } It's just the standard code from Apple's own sample code so obviously used to work: https://developer.apple.com/documentation/AVFoundation/capturing-depth-using-the-lidar-camera Does it fail because Apple have silently dumped support for the older LiDAR sensor used prior to the M4 iPad Pro, or is there another reason? What about the 5th and 6th gen iPad Pro, does it still work on those?
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505
Nov ’25
PHPhotoLibrary.performChanges completionHandler not called when deleting assets on iOS 26
In my app, I use api provided in Photos framework to delete specified photo. But after upgrading to iOS 26, the delete function in some iOS device no longer work. The api will never triggers the system confirmation dialog, and the completionHandler is never called. In the iOS Photos app, deletion works correctly on the same assets, but calling the API from my app does not work. Steps to Reproduce Make sure the app has Full Photo Library Access. Execute the following code: PHPhotoLibrary.shared().performChanges({ let assetsToBeDeleted = PHAsset.fetchAssets(withLocalIdentifiers: delUrls, options: nil) PHAssetChangeRequest.deleteAssets(assetsToBeDeleted) }, completionHandler: completionHandler) Expected Behavior The system should present a confirmation dialog asking the user to delete the selected photos. After the user confirms, the deletion should occur, and the completionHandler should be called with success or error. Actual Behavior The system delete confirmation dialog does not appear. The completionHandler is never called. Environment iOS Versions: 26.1 / 26.0.1 It looks like api bug. I want to check Is it a know issue and will be fixed. Thanks
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307
Nov ’25
APMP & Photography?
Hi, I'm a fan of the gallery in vision pro which has video as well as still photography but I'm wondering if Apple has considered adding the projected media tags to heic so that we can go that next step from Spatial photos to Immersive photos. I have a device that can give me 12k x 6k fisheye images in HDR, but it can't do it at a framerate or resolution that's good enough for video, so I want to cut my losses and show off immersive photos instead. Is there something Apple is already working on for APMP stills or should I create my own app that reads metadata inside a HEIC that I infer in a similar way to the demo "ProjectedMediaConversion" is doing for Video. It would be great to have 180VR photos, which could show as Spatial in a gallery view, but going immersive would half-surround you instead of floating in the blurred view. I think that would be a pretty amazing effect.
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324
Oct ’25
How can I locate a UVC camera for PTZ control by AVCaptureDevice.unique_id
I'm writing a program to control a PTZ camera connected via USB. I can get access to target camera's unique_id, and also other infos provided by AVFoundation. But I don't know how to locate my target USB device to send a UVC ControlRequest. There's many Cameras with same VendorID and ProductID connected at a time, so I need a more exact way to find out which device is my target. It looks that the unique_id provided is (locationID<<32|VendorID<<16|ProductID) as hex string, but I'm not sure if I can always assume this behavior won't change. Is there's a document declares how AVFoundation generate the unique_id for USB camera, so I can assume this convert will always work? Or is there's a way to send a PTZ control request to AVCaptureDevice? https://stackoverflow.com/questions/40006908/usb-interface-of-an-avcapturedevice I have seen this similar question. But I'm worrying that Exacting LocationID+VendorID+ProductID from unique_id seems like programming to implementation instead of interface. So, if there's any other better way to control my camera? here's my example code for getting unique_id: // // camera_unique_id_test.mm // // 测试代码:使用C++获取当前系统摄像头的AVCaptureDevice unique_id // // 编译命令: // clang++ -framework AVFoundation -framework CoreMedia -framework Foundation // camera_unique_id_test.mm -o camera_unique_id_test // #include <iostream> #include <string> #include <vector> #import <AVFoundation/AVFoundation.h> #import <Foundation/Foundation.h> struct CameraInfo { std::string uniqueId; }; std::vector<CameraInfo> getAllCameraDevices() { std::vector<CameraInfo> cameras; @autoreleasepool { NSArray<AVCaptureDevice*>* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; AVCaptureDevice* defaultDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; // 遍历所有设备 for (AVCaptureDevice* device in devices) { CameraInfo info; // 获取unique_id info.uniqueId = std::string([device.uniqueID UTF8String]); cameras.push_back(info); } } return cameras; } int main(int argc, char* argv[]) { std::vector<CameraInfo> cameras = getAllCameraDevices(); for (size_t i = 0; i < cameras.size(); i++) { const CameraInfo& camera = cameras[i]; std::cout << " 设备 " << (i + 1) << ":" << std::endl; std::cout << " unique_id: " << camera.uniqueId << std::endl; } return 0; } and here's my code for UVC control: // clang++ -framework Foundation -framework IOKit uvc_test.cpp -o uvc_test #include <iostream> #include <CoreFoundation/CoreFoundation.h> #include <IOKit/IOCFPlugIn.h> #include <IOKit/IOKitLib.h> #include <IOKit/IOMessage.h> #include <IOKit/usb/IOUSBLib.h> #include <IOKit/usb/USB.h> CFStringRef CreateCFStringFromIORegistryKey(io_service_t ioService, const char* key) { CFStringRef keyString = CFStringCreateWithCString(kCFAllocatorDefault, key, kCFStringEncodingUTF8); if (!keyString) return nullptr; CFStringRef result = static_cast<CFStringRef>( IORegistryEntryCreateCFProperty(ioService, keyString, kCFAllocatorDefault, kIORegistryIterateRecursively)); CFRelease(keyString); return result; } std::string GetStringFromIORegistry(io_service_t ioService, const char* key) { CFStringRef cfString = CreateCFStringFromIORegistryKey(ioService, key); if (!cfString) return ""; char buffer[256]; Boolean success = CFStringGetCString(cfString, buffer, sizeof(buffer), kCFStringEncodingUTF8); CFRelease(cfString); return success ? std::string(buffer) : std::string(""); } uint32_t GetUInt32FromIORegistry(io_service_t ioService, const char* key) { CFStringRef keyString = CFStringCreateWithCString(kCFAllocatorDefault, key, kCFStringEncodingUTF8); if (!keyString) return 0; CFNumberRef number = static_cast<CFNumberRef>( IORegistryEntryCreateCFProperty(ioService, keyString, kCFAllocatorDefault, kIORegistryIterateRecursively)); CFRelease(keyString); if (!number) return 0; uint32_t value = 0; CFNumberGetValue(number, kCFNumberSInt32Type, &value); CFRelease(number); return value; } int main() { // Get matching dictionary for USB devices CFMutableDictionaryRef matchingDict = IOServiceMatching(kIOUSBDeviceClassName); // Get iterator for matching services io_iterator_t serviceIterator; IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &serviceIterator); // Iterate through matching devices io_service_t usbService; while ((usbService = IOIteratorNext(serviceIterator))) { uint32_t locationId = GetUInt32FromIORegistry(usbService, "locationID"); uint32_t vendorId = GetUInt32FromIORegistry(usbService, "idVendor"); uint32_t productId = GetUInt32FromIORegistry(usbService, "idProduct"); IOCFPlugInInterface** plugInInterface = nullptr; IOUSBDeviceInterface** deviceInterface = nullptr; SInt32 score; // Get device plugin interface IOCreatePlugInInterfaceForService(usbService, kIOUSBDeviceUserClientTypeID, kIOCFPlugInInterfaceID, &plugInInterface, &score); // Get device interface (*plugInInterface) ->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID), (LPVOID*)&deviceInterface); (*plugInInterface)->Release(plugInInterface); // Try to find UVC control interface using CreateInterfaceIterator io_iterator_t interfaceIterator; IOUSBFindInterfaceRequest interfaceRequest; interfaceRequest.bInterfaceClass = kUSBVideoInterfaceClass; // 14 interfaceRequest.bInterfaceSubClass = kUSBVideoControlSubClass; // 1 interfaceRequest.bInterfaceProtocol = kIOUSBFindInterfaceDontCare; interfaceRequest.bAlternateSetting = kIOUSBFindInterfaceDontCare; (*deviceInterface) ->CreateInterfaceIterator(deviceInterface, &interfaceRequest, &interfaceIterator); (*deviceInterface)->Release(deviceInterface); io_service_t usbInterface = IOIteratorNext(interfaceIterator); IOObjectRelease(interfaceIterator); if (usbInterface) { std::cout << "Get UVC device with:" << std::endl; std::cout << "locationId: " << std::hex << locationId << std::endl; std::cout << "vendorId: " << std::hex << vendorId << std::endl; std::cout << "productId: " << std::hex << productId << std::endl << std::endl; IOObjectRelease(usbInterface); } IOObjectRelease(usbService); } IOObjectRelease(serviceIterator); }
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349
Oct ’25
Convert CoreAudio AudioObjectID to IOUSB LocationID
Is there a recommended way on macOS 26 Tahoe to take a CoreAudio AudioObjectID and use it to lookup the underlying USB LocationID? I previously used AudioObjectID to query the corresponding DeviceUID with kAudioDevicePropertyDeviceUID. Then I queried for the IOService matching kIOAudioEngineClassName with property kIOAudioEngineGlobalUniqueIDKey matching DeviceUID, and I loaded kUSBDevicePropertyLocationID from the result. This fails on macOS 26, because the IO Registry for the device has an entry for usbaudiod rather than AppleUSBAudioEngine, and usbaudiod does not include a kIOAudioEngineGlobalUniqueIDKey property (or any other property to map it to a CoreAudio DeviceUID). My use-case here is a piece of audio recording software that allows configuring a set of supported audio devices via USB HID prior to recording. I present the user with a list of CoreAudio devices to use, but without a way to lookup the underlying USB LocationID, I cannot guarantee that the configured device matches the selected device (e.g. if the user plugged in two identical microphones).
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609
Sep ’25
How to synchronize the clock sources of two audio devices
I created a virtual audio device to capture system audio with a sample rate of 44.1 kHz. After capturing the audio, I forward it to the hardware sound card using AVAudioEngine, also with a sample rate of 44.1 kHz. However, due to the clock sources being unsynchronized, problems occur after a period of playback. How can I retrieve the clock source of the hardware device and set it for the virtual device?
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315
May ’25
PHImageManager.requestImageDataAndOrientation callback is never called
I occasionally receive reports from users that photo import from the Photos library gets stuck and the progress appears to stop indefinitely. I’m using the following APIs (code to be added): func fetchAsset(_ asset: PHAsset) { let options = PHImageRequestOptions() options.deliveryMode = .highQualityFormat options.resizeMode = .exact options.isSynchronous = false options.isNetworkAccessAllowed = true options.progressHandler = { (progress, error, stop, info) in // 🚨 never called } let requestId = PHImageManager.default().requestImageDataAndOrientation( for: asset, options: options ) { data, _, _, info in // 🚨 never called } } Due to repeated reports, I added detailed logs inside the callback closures. Based on the logs, it looks like the request keeps waiting without any callbacks being invoked — neither the progressHandler nor the completion block of requestImageDataAndOrientation is called. This happens not only with the PHImageManager approach, but also when using PHAsset with PHContentEditingInputRequestOptions — the completion callback is not invoked as well. func fetchAssetByContentEditingInput(_ asset: PHAsset) { let options = PHContentEditingInputRequestOptions() options.isNetworkAccessAllowed = true asset.requestContentEditingInput(with: nil) { contentEditingInput, info in // 🚨 never called } } I suspect this is related to iCloud Photos. Here is what I confirmed from affected users: 1. Using the native picker, iCloud download proceeds normally and the photo can be attached. However, using the PHImageManager-based approach in my app, the same photo cannot be attached. 2. Even after verifying that the photo has been fully downloaded from iCloud (e.g., by trying “Export Unmodified Originals” in the Photos app as described here: https://support.apple.com/en-us/111762, and confirming the iCloud download progress completed), the callback is still not invoked for that asset. Detailed flow for (1): • I asked the user to attach the problematic photo (the one where callbacks never fire) using the native photo picker (UIImagePickerController). • The UI showed “Downloading from iCloud” progress. • The progress advanced and the photo was attached successfully. • Then I asked the user to attach the same photo again using my custom photo picker (which uses the PHImageManager APIs mentioned above). • The progress did not advance. • No callbacks were invoked. • The operation waited indefinitely and never completed. Workaround / current behavior: • If I ask users to force-quit and relaunch the app and try again, about 6 out of 10 users can attach successfully afterward. • The remaining ~4 out of 10 users still cannot attach even after relaunching. • For users who are not fixed immediately after relaunch, it seems to resolve naturally after some time. I’ve seen similar reports elsewhere, so I’m wondering if Apple is already aware of an internal issue related to this. If there is any known information, guidance, or recommended workaround, I would appreciate it. I also logged the properties of affected PHAssets (metadata) when the issue occurs, and I can share them below if that helps troubleshooting: [size=3.91MB] [PHAssetMediaSubtype(rawValue: 528)+DepthEffect | userLibrary | (4284x5712) | adjusted=true] [size=3.91MB] [PHAssetMediaSubtype(rawValue: 528)+DepthEffect | userLibrary | (4284x5712) | adjusted=true] [size=2.72MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true] [size=2.72MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true] [size=2.49MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true] [size=2.49MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true]
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382
Jan ’26
Dell monitor volume control issue on iMac via USB-C
I have a new 2725QC (Dell) Monitor that uses USB-C connection to connect with the iMac (2019, 27 inch) through the back port but the problem is that the volume control can currently only be done from the hardware, not the software control using the Apple keyboard. What should I do in terms of writing code to do this (Swift or Obj-C)? Is there a third-party solution for Intel iMac and ARM Mac?
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264
Jan ’26
Why is my YCbCr to sRGB camera pipeline brighter Than Preview Layer? (420YpCbCr8BiPlanarFullRange, AVCaptureVideoPreviewLayer)
Hi all, I'm working on a custom Metal-based video pipeline using AVCaptureVideoDataOutput, and I've run into an unexpected issue related to exposure. Setup: I'm capturing video frames using kCVPixelFormatType_420YpCbCr8BiPlanarFullRange. In my Metal shader, I: Convert YCbCr (full range Rec.709) to linear Rec.709 RGB. Apply Rec.709 → sRGB gamma encoding. Output to .bgra8Unorm_srgb via MTKView. Everything renders correctly in terms of colorspace math, but the image appears significantly brighter (~+3 stops EV) compared to AVCaptureVideoPreviewLayer and the native iOS Camera app under the same camera exposure settings. What I’ve verified: The color transforms are correct: YCbCr709 to RGB, then linear to sRGB. I'm not applying any tone mapping or aggressive look LUTs yet. Camera exposure is locked using: device.setExposureModeCustom(duration: ..., iso: ...) The same EV (e.g., ISO 50, 1/125s, f/5.6) on my iPhone appears visually 3 stops brighter than on my digital cameras (Sony/Canon etc). To match the look of the preview layer or camera app, I have to simulate a ~–3 EV shift in my custom pipeline. Questions: Is AVCaptureVideoPreviewLayer applying extra tone mapping, digital gain, or contrast shaping (like OOTF etc)? Does the camera ISP expose "hotter" (i.e., with more light) internally for the preview layer than what we get in video frame buffers? Is there a standard way to compensate for this ISP behavior in custom pipelines using AVCaptureVideoDataOutput? Can this be accounted for using metadata (e.g., exposure bias, gain, gamma curve)?
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263
Sep ’25
How to reliably detect user-modified photos?
I'm developing a photo backup app. To detect newly added or edited photos since the app launched, I keep a local dictionary in the format [localIdentifier: modification_date]. However, PHAsset.modificationDate is not reliable. It often changes unexpectedly, possibly due to system operations like iCloud metadata updates. Is there a more reliable way to detect whether a photo has been modified by user since the last app launch? I'm thinking about using content hash instead, but I'm not sure how heavy this operation is in terms of performance.
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98
Aug ’25
AVAudioSession.outputVolume does not reflect system volume changes made while app is in background
I have a question regarding the behavior of AVAudioSession.sharedInstance().outputVolume. Observed behavior: When the app is in the foreground, I read audioSession.outputVolume (for example, 0.1). The app is then moved to the background. While the app is in the background, the user changes the system volume using the hardware buttons (for example, to 0.5). When the app returns to the foreground, audioSession.outputVolume still reports the previous value (0.1). From my testing, outputVolume only seems to update when the system volume is changed while the app is in the foreground. Volume changes made while the app is in the background are not reflected when the app returns to the foreground. Questions: According to Apple’s documentation for AVAudioSession.outputVolume: “The systemwide output volume set by the user.” https://developer.apple.com/documentation/avfaudio/avaudiosession/outputvolume However, based on our testing on iOS 18.6.2 and iOS 18.1, the observed behavior seems to differ from this description. Questions: The documentation states that outputVolume represents the system-wide volume set by the user. In our testing, the value does not reflect volume changes made while the app is in the background and only updates when the app is in the foreground.Is this the expected behavior of AVAudioSession.outputVolume? Is there any other recommended way in Swift to retrieve the current system volume that reflects user changes made both while the app is in the foreground and while it is in the background? Any clarification on the intended behavior or recommended handling would be greatly appreciated.
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250
5d
failed to set category, reason: 未能完成操作。(OSStatus错误4097。)
When using the [AVAudioSession setCategory:withOptions:error:] API, the call hangs for a long time and eventually returns an error.This issue occurs on iOS 16, and did not appear in earlier versions. Thread 135: 0 libsystem_kernel.dylib 0x00000002478e3cd4 _mach_msg2_trap :8 (in libsystem_kernel.dylib) 1 libsystem_kernel.dylib 0x00000002478e7214 _mach_msg_overwrite :428 (in libsystem_kernel.dylib) 2 libsystem_kernel.dylib 0x00000002478e705c _mach_msg :24 (in libsystem_kernel.dylib) 3 libdispatch.dylib 0x00000001d63ffe84 __dispatch_mach_send_and_wait_for_reply :548 (in libdispatch.dylib) 4 libdispatch.dylib 0x00000001d6400224 _dispatch_mach_send_with_result_and_wait_for_reply :60 (in libdispatch.dylib) 5 libxpc.dylib 0x00000001b2114e04 _xpc_connection_send_message_with_reply_sync :256 (in libxpc.dylib) 6 Foundation 0x000000019b6249f0 ___NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY__ :16 (in Foundation) 7 Foundation 0x000000019c06d1b4 -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] :2100 (in Foundation) 8 CoreFoundation 0x000000019dfcb1cc ____forwarding___ :1072 (in CoreFoundation) 9 CoreFoundation 0x000000019dfd3200 ___forwarding_prep_0___ :96 (in CoreFoundation) 10 AudioSession 0x00000001c77498b0 __ZN4avas6client11SessionCore10HandlePingEv :192 (in AudioSession) 11 AudioSession 0x00000001c77497b0 ____ZN4avas6client11SessionCore12DispatchPingEv_block_invoke :52 (in AudioSession) 12 libdispatch.dylib 0x00000001d63e4adc __dispatch_call_block_and_release :32 (in libdispatch.dylib) 13 libdispatch.dylib 0x00000001d63fe7ec __dispatch_client_callout :16 (in libdispatch.dylib) 14 libdispatch.dylib 0x00000001d63ed468 __dispatch_lane_serial_drain :740 (in libdispatch.dylib) 15 libdispatch.dylib 0x00000001d63edf78 __dispatch_lane_invoke :440 (in libdispatch.dylib) 16 libdispatch.dylib 0x00000001d63f6f48 __dispatch_root_queue_drain :364 (in libdispatch.dylib) 17 libdispatch.dylib 0x00000001d63f6d08 __dispatch_worker_thread :268 (in libdispatch.dylib) 18 libsystem_pthread.dylib 0x00000001f9ff144c __pthread_start :136 (in libsystem_pthread.dylib) 19 libsystem_pthread.dylib 0x00000001f9fed8cc _thread_start :8 (in libsystem_pthread.dylib) Thread 132: 0 libsystem_kernel.dylib 0x00000002478e3cd4 _mach_msg2_trap :8 (in libsystem_kernel.dylib) 1 libsystem_kernel.dylib 0x00000002478e7214 _mach_msg_overwrite :428 (in libsystem_kernel.dylib) 2 libsystem_kernel.dylib 0x00000002478e705c _mach_msg :24 (in libsystem_kernel.dylib) 3 libdispatch.dylib 0x00000001d63ffe84 __dispatch_mach_send_and_wait_for_reply :548 (in libdispatch.dylib) 4 libdispatch.dylib 0x00000001d6400224 _dispatch_mach_send_with_result_and_wait_for_reply :60 (in libdispatch.dylib) 5 libxpc.dylib 0x00000001b2114e04 _xpc_connection_send_message_with_reply_sync :256 (in libxpc.dylib) 6 Foundation 0x000000019b6249f0 ___NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY__ :16 (in Foundation) 7 Foundation 0x000000019c06d1b4 -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] :2100 (in Foundation) 8 CoreFoundation 0x000000019dfcb1cc ____forwarding___ :1072 (in CoreFoundation) 9 CoreFoundation 0x000000019dfd3200 ___forwarding_prep_0___ :96 (in CoreFoundation) 10 AudioSession 0x00000001c7754198 __ZNK4avas6client11SessionCore18SetBatchPropertiesEP12NSDictionaryIP8NSStringPU25objcproto14NSSecureCoding11objc_objectEPU15__autoreleasingP7NSArrayIPS2_IS4_P8NSNumberEENS_30AVAudioSessionBatchSetStrategyEbb :548 (in AudioSession) 11 AudioSession 0x00000001c7753e58 __ZNK4avas6client11SessionCore20SetBatchPropertiesMXEP12NSDictionaryIP8NSStringPU25objcproto14NSSecureCoding11objc_objectE :92 (in AudioSession) 12 AudioSession 0x00000001c775179c __ZN4avas6client11SessionCore11setCategoryEP8NSStringS3_32AVAudioSessionRouteSharingPolicym :472 (in AudioSession) 13 AudioSession 0x00000001c7768f88 -[AVAudioSession setCategory:withOptions:error:] :68 (in AudioSession) 14 AlipayWallet 0x000000010140580c -[AVAudioSession(APMHook) apmhook_setCategory:withOptions:error:] APMHookAudioSession.m:35 (in AlipayWallet) 15 AlipayWallet 0x00000001014001a4 -[APMAudioSessionManager resume] APMAudioSessionManager.m:718 (in AlipayWallet) 16 libdispatch.dylib 0x00000001d63e4adc __dispatch_call_block_and_release :32 (in libdispatch.dylib) 17 libdispatch.dylib 0x00000001d63fe7ec __dispatch_client_callout :16 (in libdispatch.dylib) 18 libdispatch.dylib 0x00000001d63ed468 __dispatch_lane_serial_drain :740 (in libdispatch.dylib) 19 libdispatch.dylib 0x00000001d63edf44 __dispatch_lane_invoke :388 (in libdispatch.dylib) 20 libdispatch.dylib 0x00000001d63f83ec __dispatch_root_queue_drain_deferred_wlh :292 (in libdispatch.dylib) 21 libdispatch.dylib 0x00000001d63f7ce4 __dispatch_workloop_worker_thread :692 (in libdispatch.dylib) 22 libsystem_pthread.dylib 0x00000001f9fee3b8 __pthread_wqthread :292 (in libsystem_pthread.dylib) 23 libsystem_pthread.dylib 0x00000001f9fed8c0 _start_wqthread :8 (in libsystem_pthread.dylib)
2
0
770
Feb ’26
"Baking together" two audio tracks into one for drag-and-drop
Hi all, with my app ScreenFloat, you can record your screen, along with system- and microphone audio. Those two audio feeds are recorded into separate audio tracks in order to individually remove or edit them later on. Now, these recordings you create with ScreenFloat can be drag-and-dropped to other apps instantly. So far, so good, but some apps, like Slack, or VLC, or even websites like YouTube, do not play back multiple audio tracks, just one. So what I'm trying to do is, on dragging the video recording file out of ScreenFloat, instantly baking together the two individual audio tracks into one, and offering that new file as the drag and drop file, so that all audio is played in the target app. But it's slow. I mean, it's actually quite fast, but for drag and drop, it's slow. My approach is this: "Bake together" the two audio tracks into a one-track m4a audio file using AVMutableAudioMix and AVAssetExportSession Take the video track, add the new audio file as an audio track to it, and render that out using AVAssetExportSession For a quick benchmark, a 3'40'' movie, step 1 takes ~1.7 seconds, and step two adds another ~1.5 seconds, so we're at ~3.2 seconds. That's an eternity for a drag and drop, where the user might cancel if there's no immediate feedback. I could also do it in one step, but then I couldn't use the AV*Passthrough preset, and that makes it take around 32 seconds then, because I assume it touches the video data (which is unnecessary in this case, so I think the two-step approach here is the fastest). So, my question is, is there a faster way? The best idea I can come up with right now is, when initially recording the screen with system- and microphone audio as separate tracks, to also record both of them into a third, muted, "hidden" track I could use later on, basically eliminating the need for step one and just ripping the two single audio tracks out of the movie and only have the video and the "hidden" track (then unmuted), but I'd still have a ~1.5 second delay there. Also, there's the processing and data overhead (basically doubling the movie's audio data). All this would be great for an export operation (where one expects it to take a little time), but for a drag-and-drop operation, it's not ideal. I've discarded the idea of doing a promise file drag, because many apps do not accept those, and I want to keep wide compatibility with all sorts of apps. I'd appreciate any ideas or pointers. Thank you kindly, Matthias
2
0
737
Mar ’25
AVPlayerViewController crashes
I have a crash related to playing video in AVPlayerViewController and AVQueuePlayer. I download the video locally from the network and then initialize it using AVAsset and AVPlayerItem. Can't reproduce locally, but crashes occur from firebase crashlytics only for users starting with iOS 18.4.0 with this trace: Crashed: com.apple.avkit.playerControllerBackgroundQueue 0 libobjc.A.dylib 0x1458 objc_retain + 16 1 libobjc.A.dylib 0x1458 objc_retain_x0 + 16 2 AVKit 0x12afdc __77-[AVPlayerController currentEnabledAssetTrackForMediaType:completionHandler:]_block_invoke + 108 3 libdispatch.dylib 0x1aac _dispatch_call_block_and_release + 32 4 libdispatch.dylib 0x1b584 _dispatch_client_callout + 16 5 libdispatch.dylib 0x6560 _dispatch_continuation_pop + 596 6 libdispatch.dylib 0x5bd4 _dispatch_async_redirect_invoke + 580 7 libdispatch.dylib 0x13db0 _dispatch_root_queue_drain + 364 8 libdispatch.dylib 0x1454c _dispatch_worker_thread2 + 156 9 libsystem_pthread.dylib 0x4624 _pthread_wqthread + 232 10 libsystem_pthread.dylib 0x19f8 start_wqthread + 8
2
3
263
May ’25
After iOS 18.5, the AVFoundation AVCaptureSessionInterruptionReason.videoDeviceNotAvailableWithMultipleForegroundApps error has caused a significant increase in camera black screen issues.
Issue: After iOS 18.5 release, our app is experiencing a significant increase in AVCaptureSessionInterruptionReason.videoDeviceNotAvailableWithMultipleForegroundApps errors. Details: Our camera-related code has not been updated recently.However, we've observed that the error rate has significantly increased starting from May 2025. The error rate has risen from approximately 0.02% (2 in 10,000 users) to 0.1% (1 in 1,000 users). This represents a 5x increase in error occurrence. The frequency has increased noticeably since iOS 18.5 This is affecting our app's camera functionality and user experience Questions: Are there any known changes in iOS 18.5 regarding camera access management? What are the recommended best practices to handle this interruption reason? Are there any API changes we should be aware of? Best, Shay
2
1
495
Oct ’25
iOS 26: Underexposed image in exposure bracket appears clamped vs single capture
Hello, I have an iOS camera app that captures exposure brackets and performs custom HDR processing. On iOS 26, I’m observing a visual difference between: a single photo captured at –2 EV, and the –2 EV frame from an exposure bracket (–2 / 0 / +2 EV). On iOS 26: The single –2 EV image looks natural and consistent. The –2 EV image from the bracket appears clamped / distorted, most noticeably in high dynamic range scenes (highlight compression and loss of detail). On iOS 18, both approaches produce visually identical and correct –2 EV images. The issue only appears for bracketed captures on iOS 26. Attachments (examples) iOS 26 Single capture –2 EV (JPEG): /Users/danilobudimir/Downloads/ios26SingleImage/JPEG image-4006-8B77-51-0.jpeg Single capture –2 EV — Capture report (dumped settings): /Users/danilobudimir/Downloads/ios26SingleImage/UnderExposureDebug_CaptureReport_2026-01-09T15-59-20Z.md Bracket capture –2 EV frame (JPEG): /Users/danilobudimir/Downloads/bracket_iOS26/JPEG image-45CE-9793-A5-0.jpeg Bracket capture — Capture report (dumped settings): /Users/danilobudimir/Downloads/bracket_iOS26/UnderExposureDebug_CaptureReport_2026-01-09T15-55-42Z.md iOS 18 Single capture –2 EV (JPEG): /Users/danilobudimir/Downloads/ios18SingleImage/JPEG image-47FD-AF73-28-0.jpeg Single capture –2 EV — Capture report: /Users/danilobudimir/Downloads/ios18SingleImage/UnderExposureDebug_CaptureReport_2026-01-09T16-25-27Z.md Bracket capture — –2 EV frame (JPEG): /Users/danilobudimir/Downloads/bracket_iOS18/JPEG image-4A4C-9E93-46-0.jpeg Bracket capture — Capture report: /Users/danilobudimir/Downloads/bracket_iOS18/UnderExposureDebug_CaptureReport_2026-01-09T16-27-23Z.md Question Is there any new behavior in iOS 26 AVFoundation related to: AVCapturePhotoBracketSettings, tone mapping / HDR preprocessing, or internal image processing applied specifically to bracketed frames? Is there a new flag, format requirement or opt-out mechanism required to preserve linear underexposed frames in exposure brackets?
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2
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855
Activity
Jan ’26
AirPlay v1 is broken in iOS 18.4?
After upgrading to iOS 18.4, I'm no longer able to establish an AirPlay v1 connection to an audio system. The symptom is that the AirPlay route picker just spins when trying to connect to an audio system. It eventually gives up. I tested this on an iPhone 14, connecting to a HomePod, AirPort express, AppleTV and a Wiim Pro. If I try connecting with AirPlay v2, ex: using Apple Music, the connection succeeds and audio can be played. I'm the developer of an app that plays audio over AirPlay while also recording. My app has to use AirPlay v1 because AvAudioSession doesn't allow the policy .longFormAudio when the category is .playAndRecord. This issue is a real pain as it means my app is suddenly broken for many thousands of users. Is anyone else seeing this issue? Any suggestions for a workaround?
Replies
2
Boosts
3
Views
527
Activity
Jun ’25
dlsym cannot find symbol g_dwILResult when debugging an audio plugin
I am trying to debug the AAX version of my plugin (MIDI effect) on Pro Tools, but I am getting the following error (Mac console) when attempting to load it: dlsym cannot find symbol g_dwILResult in CFBundle etc.. I used Xcode 16.4 to build the plugin. Has anybody come across the same or a similar message? Best, Achillefs Axart Labs
Replies
2
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0
Views
565
Activity
Sep ’25
CoreMediaErrorDomain -12888: Bandwidth down-stepping when using 2sec segment duration
the problem is when using HLS live stream with AVPlayer on iOS/ tvOS the player chooses first highest bandwidth then slowly steps down to lowest (within 1-3min) and eventually steps up again then repeats to step down. the AVPlayer error log sends events: errorStatusCode: -12888, errorDomain: Optional("CoreMediaErrorDomain"), errorComment: Optional("The operation couldn't be completed. (CoreMediaErrorDomain error -12888 - Playlist File unchanged for longer than 1.5 * target duration we use standard segments in CMAF format, 2sec duration #EXTM3U #EXT-X-VERSION:6 #EXT-X-TARGETDURATION:2 #EXT-X-MEDIA-SEQUENCE:147065903 #EXT-X-MAP:URI="video_1_4660000_init.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2" #EXT-X-PROGRAM-DATE-TIME:2025-04-30T12:51:07 #EXTINF:2.000, video_1_4660000_t17460174670001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 #EXTINF:2.000, video_1_4660000_t17460174690001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 #EXTINF:2.000, video_1_4660000_t17460174710001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 when using 6sec segments the player stays stable at highest bandwidth. is there a way to avoid this error? in AVPlayer or HLS configuration?
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2
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0
Views
390
Activity
May ’25
Logged error/warning in FigCaptureSourceRemote when capturing a photo
I'm using this library: https://github.com/Yummypets/YPImagePicker to capture photos. I've modified it slightly, and I'm using an older version. When testing on my iPhone 16e, ios 26, whenever I take a photo, I get the following two error messages: <<<< FigXPCUtilities >>>> signalled err=-17281 at <>:302 <<<< FigCaptureSourceRemote >>>> Fig assert: "err == 0 " at bail (FigCaptureSourceRemote.m:569) - (err=-17281) These error messages appear, but as far as I can tell, the photo comes through OK, and I can save the data no problem. I've even removed all my handling code to see if it was something I was doing. I don't really want to ship with these errors showing, but I also have no idea what can be causing this error to appear. chatgpt was not helpful diagnosing this. Does anyone know what can cause this error Is there a way I can see the source code to figure out if there's something I'm doing wrong here? It really seems like this is an internal apple error, or else I would have expected more details on the error relating to the code I've written. Any clues would be appreciated!
Replies
2
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2
Views
782
Activity
Dec ’25
builtInLiDARDepthCamera doesn't work on the 2020 iPad Pro on iOS 26
On iOS 26.1, this throws on the 2020 iPad Pro (4th gen) but works fine on an M4 iPad Pro or iPhone 15 Pro: guard let device = AVCaptureDevice.default(.builtInLiDARDepthCamera, for: .video, position: .back) else { throw ConfigurationError.lidarDeviceUnavailable } It's just the standard code from Apple's own sample code so obviously used to work: https://developer.apple.com/documentation/AVFoundation/capturing-depth-using-the-lidar-camera Does it fail because Apple have silently dumped support for the older LiDAR sensor used prior to the M4 iPad Pro, or is there another reason? What about the 5th and 6th gen iPad Pro, does it still work on those?
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2
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0
Views
505
Activity
Nov ’25
PHPhotoLibrary.performChanges completionHandler not called when deleting assets on iOS 26
In my app, I use api provided in Photos framework to delete specified photo. But after upgrading to iOS 26, the delete function in some iOS device no longer work. The api will never triggers the system confirmation dialog, and the completionHandler is never called. In the iOS Photos app, deletion works correctly on the same assets, but calling the API from my app does not work. Steps to Reproduce Make sure the app has Full Photo Library Access. Execute the following code: PHPhotoLibrary.shared().performChanges({ let assetsToBeDeleted = PHAsset.fetchAssets(withLocalIdentifiers: delUrls, options: nil) PHAssetChangeRequest.deleteAssets(assetsToBeDeleted) }, completionHandler: completionHandler) Expected Behavior The system should present a confirmation dialog asking the user to delete the selected photos. After the user confirms, the deletion should occur, and the completionHandler should be called with success or error. Actual Behavior The system delete confirmation dialog does not appear. The completionHandler is never called. Environment iOS Versions: 26.1 / 26.0.1 It looks like api bug. I want to check Is it a know issue and will be fixed. Thanks
Replies
2
Boosts
1
Views
307
Activity
Nov ’25
APMP & Photography?
Hi, I'm a fan of the gallery in vision pro which has video as well as still photography but I'm wondering if Apple has considered adding the projected media tags to heic so that we can go that next step from Spatial photos to Immersive photos. I have a device that can give me 12k x 6k fisheye images in HDR, but it can't do it at a framerate or resolution that's good enough for video, so I want to cut my losses and show off immersive photos instead. Is there something Apple is already working on for APMP stills or should I create my own app that reads metadata inside a HEIC that I infer in a similar way to the demo "ProjectedMediaConversion" is doing for Video. It would be great to have 180VR photos, which could show as Spatial in a gallery view, but going immersive would half-surround you instead of floating in the blurred view. I think that would be a pretty amazing effect.
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2
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0
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324
Activity
Oct ’25
How can I locate a UVC camera for PTZ control by AVCaptureDevice.unique_id
I'm writing a program to control a PTZ camera connected via USB. I can get access to target camera's unique_id, and also other infos provided by AVFoundation. But I don't know how to locate my target USB device to send a UVC ControlRequest. There's many Cameras with same VendorID and ProductID connected at a time, so I need a more exact way to find out which device is my target. It looks that the unique_id provided is (locationID<<32|VendorID<<16|ProductID) as hex string, but I'm not sure if I can always assume this behavior won't change. Is there's a document declares how AVFoundation generate the unique_id for USB camera, so I can assume this convert will always work? Or is there's a way to send a PTZ control request to AVCaptureDevice? https://stackoverflow.com/questions/40006908/usb-interface-of-an-avcapturedevice I have seen this similar question. But I'm worrying that Exacting LocationID+VendorID+ProductID from unique_id seems like programming to implementation instead of interface. So, if there's any other better way to control my camera? here's my example code for getting unique_id: // // camera_unique_id_test.mm // // 测试代码:使用C++获取当前系统摄像头的AVCaptureDevice unique_id // // 编译命令: // clang++ -framework AVFoundation -framework CoreMedia -framework Foundation // camera_unique_id_test.mm -o camera_unique_id_test // #include <iostream> #include <string> #include <vector> #import <AVFoundation/AVFoundation.h> #import <Foundation/Foundation.h> struct CameraInfo { std::string uniqueId; }; std::vector<CameraInfo> getAllCameraDevices() { std::vector<CameraInfo> cameras; @autoreleasepool { NSArray<AVCaptureDevice*>* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; AVCaptureDevice* defaultDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; // 遍历所有设备 for (AVCaptureDevice* device in devices) { CameraInfo info; // 获取unique_id info.uniqueId = std::string([device.uniqueID UTF8String]); cameras.push_back(info); } } return cameras; } int main(int argc, char* argv[]) { std::vector<CameraInfo> cameras = getAllCameraDevices(); for (size_t i = 0; i < cameras.size(); i++) { const CameraInfo& camera = cameras[i]; std::cout << " 设备 " << (i + 1) << ":" << std::endl; std::cout << " unique_id: " << camera.uniqueId << std::endl; } return 0; } and here's my code for UVC control: // clang++ -framework Foundation -framework IOKit uvc_test.cpp -o uvc_test #include <iostream> #include <CoreFoundation/CoreFoundation.h> #include <IOKit/IOCFPlugIn.h> #include <IOKit/IOKitLib.h> #include <IOKit/IOMessage.h> #include <IOKit/usb/IOUSBLib.h> #include <IOKit/usb/USB.h> CFStringRef CreateCFStringFromIORegistryKey(io_service_t ioService, const char* key) { CFStringRef keyString = CFStringCreateWithCString(kCFAllocatorDefault, key, kCFStringEncodingUTF8); if (!keyString) return nullptr; CFStringRef result = static_cast<CFStringRef>( IORegistryEntryCreateCFProperty(ioService, keyString, kCFAllocatorDefault, kIORegistryIterateRecursively)); CFRelease(keyString); return result; } std::string GetStringFromIORegistry(io_service_t ioService, const char* key) { CFStringRef cfString = CreateCFStringFromIORegistryKey(ioService, key); if (!cfString) return ""; char buffer[256]; Boolean success = CFStringGetCString(cfString, buffer, sizeof(buffer), kCFStringEncodingUTF8); CFRelease(cfString); return success ? std::string(buffer) : std::string(""); } uint32_t GetUInt32FromIORegistry(io_service_t ioService, const char* key) { CFStringRef keyString = CFStringCreateWithCString(kCFAllocatorDefault, key, kCFStringEncodingUTF8); if (!keyString) return 0; CFNumberRef number = static_cast<CFNumberRef>( IORegistryEntryCreateCFProperty(ioService, keyString, kCFAllocatorDefault, kIORegistryIterateRecursively)); CFRelease(keyString); if (!number) return 0; uint32_t value = 0; CFNumberGetValue(number, kCFNumberSInt32Type, &value); CFRelease(number); return value; } int main() { // Get matching dictionary for USB devices CFMutableDictionaryRef matchingDict = IOServiceMatching(kIOUSBDeviceClassName); // Get iterator for matching services io_iterator_t serviceIterator; IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &serviceIterator); // Iterate through matching devices io_service_t usbService; while ((usbService = IOIteratorNext(serviceIterator))) { uint32_t locationId = GetUInt32FromIORegistry(usbService, "locationID"); uint32_t vendorId = GetUInt32FromIORegistry(usbService, "idVendor"); uint32_t productId = GetUInt32FromIORegistry(usbService, "idProduct"); IOCFPlugInInterface** plugInInterface = nullptr; IOUSBDeviceInterface** deviceInterface = nullptr; SInt32 score; // Get device plugin interface IOCreatePlugInInterfaceForService(usbService, kIOUSBDeviceUserClientTypeID, kIOCFPlugInInterfaceID, &plugInInterface, &score); // Get device interface (*plugInInterface) ->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID), (LPVOID*)&deviceInterface); (*plugInInterface)->Release(plugInInterface); // Try to find UVC control interface using CreateInterfaceIterator io_iterator_t interfaceIterator; IOUSBFindInterfaceRequest interfaceRequest; interfaceRequest.bInterfaceClass = kUSBVideoInterfaceClass; // 14 interfaceRequest.bInterfaceSubClass = kUSBVideoControlSubClass; // 1 interfaceRequest.bInterfaceProtocol = kIOUSBFindInterfaceDontCare; interfaceRequest.bAlternateSetting = kIOUSBFindInterfaceDontCare; (*deviceInterface) ->CreateInterfaceIterator(deviceInterface, &interfaceRequest, &interfaceIterator); (*deviceInterface)->Release(deviceInterface); io_service_t usbInterface = IOIteratorNext(interfaceIterator); IOObjectRelease(interfaceIterator); if (usbInterface) { std::cout << "Get UVC device with:" << std::endl; std::cout << "locationId: " << std::hex << locationId << std::endl; std::cout << "vendorId: " << std::hex << vendorId << std::endl; std::cout << "productId: " << std::hex << productId << std::endl << std::endl; IOObjectRelease(usbInterface); } IOObjectRelease(usbService); } IOObjectRelease(serviceIterator); }
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2
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0
Views
349
Activity
Oct ’25
Convert CoreAudio AudioObjectID to IOUSB LocationID
Is there a recommended way on macOS 26 Tahoe to take a CoreAudio AudioObjectID and use it to lookup the underlying USB LocationID? I previously used AudioObjectID to query the corresponding DeviceUID with kAudioDevicePropertyDeviceUID. Then I queried for the IOService matching kIOAudioEngineClassName with property kIOAudioEngineGlobalUniqueIDKey matching DeviceUID, and I loaded kUSBDevicePropertyLocationID from the result. This fails on macOS 26, because the IO Registry for the device has an entry for usbaudiod rather than AppleUSBAudioEngine, and usbaudiod does not include a kIOAudioEngineGlobalUniqueIDKey property (or any other property to map it to a CoreAudio DeviceUID). My use-case here is a piece of audio recording software that allows configuring a set of supported audio devices via USB HID prior to recording. I present the user with a list of CoreAudio devices to use, but without a way to lookup the underlying USB LocationID, I cannot guarantee that the configured device matches the selected device (e.g. if the user plugged in two identical microphones).
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2
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0
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609
Activity
Sep ’25
How to synchronize the clock sources of two audio devices
I created a virtual audio device to capture system audio with a sample rate of 44.1 kHz. After capturing the audio, I forward it to the hardware sound card using AVAudioEngine, also with a sample rate of 44.1 kHz. However, due to the clock sources being unsynchronized, problems occur after a period of playback. How can I retrieve the clock source of the hardware device and set it for the virtual device?
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315
Activity
May ’25
PHImageManager.requestImageDataAndOrientation callback is never called
I occasionally receive reports from users that photo import from the Photos library gets stuck and the progress appears to stop indefinitely. I’m using the following APIs (code to be added): func fetchAsset(_ asset: PHAsset) { let options = PHImageRequestOptions() options.deliveryMode = .highQualityFormat options.resizeMode = .exact options.isSynchronous = false options.isNetworkAccessAllowed = true options.progressHandler = { (progress, error, stop, info) in // 🚨 never called } let requestId = PHImageManager.default().requestImageDataAndOrientation( for: asset, options: options ) { data, _, _, info in // 🚨 never called } } Due to repeated reports, I added detailed logs inside the callback closures. Based on the logs, it looks like the request keeps waiting without any callbacks being invoked — neither the progressHandler nor the completion block of requestImageDataAndOrientation is called. This happens not only with the PHImageManager approach, but also when using PHAsset with PHContentEditingInputRequestOptions — the completion callback is not invoked as well. func fetchAssetByContentEditingInput(_ asset: PHAsset) { let options = PHContentEditingInputRequestOptions() options.isNetworkAccessAllowed = true asset.requestContentEditingInput(with: nil) { contentEditingInput, info in // 🚨 never called } } I suspect this is related to iCloud Photos. Here is what I confirmed from affected users: 1. Using the native picker, iCloud download proceeds normally and the photo can be attached. However, using the PHImageManager-based approach in my app, the same photo cannot be attached. 2. Even after verifying that the photo has been fully downloaded from iCloud (e.g., by trying “Export Unmodified Originals” in the Photos app as described here: https://support.apple.com/en-us/111762, and confirming the iCloud download progress completed), the callback is still not invoked for that asset. Detailed flow for (1): • I asked the user to attach the problematic photo (the one where callbacks never fire) using the native photo picker (UIImagePickerController). • The UI showed “Downloading from iCloud” progress. • The progress advanced and the photo was attached successfully. • Then I asked the user to attach the same photo again using my custom photo picker (which uses the PHImageManager APIs mentioned above). • The progress did not advance. • No callbacks were invoked. • The operation waited indefinitely and never completed. Workaround / current behavior: • If I ask users to force-quit and relaunch the app and try again, about 6 out of 10 users can attach successfully afterward. • The remaining ~4 out of 10 users still cannot attach even after relaunching. • For users who are not fixed immediately after relaunch, it seems to resolve naturally after some time. I’ve seen similar reports elsewhere, so I’m wondering if Apple is already aware of an internal issue related to this. If there is any known information, guidance, or recommended workaround, I would appreciate it. I also logged the properties of affected PHAssets (metadata) when the issue occurs, and I can share them below if that helps troubleshooting: [size=3.91MB] [PHAssetMediaSubtype(rawValue: 528)+DepthEffect | userLibrary | (4284x5712) | adjusted=true] [size=3.91MB] [PHAssetMediaSubtype(rawValue: 528)+DepthEffect | userLibrary | (4284x5712) | adjusted=true] [size=2.72MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true] [size=2.72MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true] [size=2.49MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true] [size=2.49MB] [PHAssetMediaSubtype(rawValue: 16)+DepthEffect | userLibrary | (3024x4032) | adjusted=true]
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382
Activity
Jan ’26
Dell monitor volume control issue on iMac via USB-C
I have a new 2725QC (Dell) Monitor that uses USB-C connection to connect with the iMac (2019, 27 inch) through the back port but the problem is that the volume control can currently only be done from the hardware, not the software control using the Apple keyboard. What should I do in terms of writing code to do this (Swift or Obj-C)? Is there a third-party solution for Intel iMac and ARM Mac?
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2
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264
Activity
Jan ’26
Why is my YCbCr to sRGB camera pipeline brighter Than Preview Layer? (420YpCbCr8BiPlanarFullRange, AVCaptureVideoPreviewLayer)
Hi all, I'm working on a custom Metal-based video pipeline using AVCaptureVideoDataOutput, and I've run into an unexpected issue related to exposure. Setup: I'm capturing video frames using kCVPixelFormatType_420YpCbCr8BiPlanarFullRange. In my Metal shader, I: Convert YCbCr (full range Rec.709) to linear Rec.709 RGB. Apply Rec.709 → sRGB gamma encoding. Output to .bgra8Unorm_srgb via MTKView. Everything renders correctly in terms of colorspace math, but the image appears significantly brighter (~+3 stops EV) compared to AVCaptureVideoPreviewLayer and the native iOS Camera app under the same camera exposure settings. What I’ve verified: The color transforms are correct: YCbCr709 to RGB, then linear to sRGB. I'm not applying any tone mapping or aggressive look LUTs yet. Camera exposure is locked using: device.setExposureModeCustom(duration: ..., iso: ...) The same EV (e.g., ISO 50, 1/125s, f/5.6) on my iPhone appears visually 3 stops brighter than on my digital cameras (Sony/Canon etc). To match the look of the preview layer or camera app, I have to simulate a ~–3 EV shift in my custom pipeline. Questions: Is AVCaptureVideoPreviewLayer applying extra tone mapping, digital gain, or contrast shaping (like OOTF etc)? Does the camera ISP expose "hotter" (i.e., with more light) internally for the preview layer than what we get in video frame buffers? Is there a standard way to compensate for this ISP behavior in custom pipelines using AVCaptureVideoDataOutput? Can this be accounted for using metadata (e.g., exposure bias, gain, gamma curve)?
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2
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263
Activity
Sep ’25
How to reliably detect user-modified photos?
I'm developing a photo backup app. To detect newly added or edited photos since the app launched, I keep a local dictionary in the format [localIdentifier: modification_date]. However, PHAsset.modificationDate is not reliable. It often changes unexpectedly, possibly due to system operations like iCloud metadata updates. Is there a more reliable way to detect whether a photo has been modified by user since the last app launch? I'm thinking about using content hash instead, but I'm not sure how heavy this operation is in terms of performance.
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2
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98
Activity
Aug ’25
AVAudioSession.outputVolume does not reflect system volume changes made while app is in background
I have a question regarding the behavior of AVAudioSession.sharedInstance().outputVolume. Observed behavior: When the app is in the foreground, I read audioSession.outputVolume (for example, 0.1). The app is then moved to the background. While the app is in the background, the user changes the system volume using the hardware buttons (for example, to 0.5). When the app returns to the foreground, audioSession.outputVolume still reports the previous value (0.1). From my testing, outputVolume only seems to update when the system volume is changed while the app is in the foreground. Volume changes made while the app is in the background are not reflected when the app returns to the foreground. Questions: According to Apple’s documentation for AVAudioSession.outputVolume: “The systemwide output volume set by the user.” https://developer.apple.com/documentation/avfaudio/avaudiosession/outputvolume However, based on our testing on iOS 18.6.2 and iOS 18.1, the observed behavior seems to differ from this description. Questions: The documentation states that outputVolume represents the system-wide volume set by the user. In our testing, the value does not reflect volume changes made while the app is in the background and only updates when the app is in the foreground.Is this the expected behavior of AVAudioSession.outputVolume? Is there any other recommended way in Swift to retrieve the current system volume that reflects user changes made both while the app is in the foreground and while it is in the background? Any clarification on the intended behavior or recommended handling would be greatly appreciated.
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250
Activity
5d
failed to set category, reason: 未能完成操作。(OSStatus错误4097。)
When using the [AVAudioSession setCategory:withOptions:error:] API, the call hangs for a long time and eventually returns an error.This issue occurs on iOS 16, and did not appear in earlier versions. Thread 135: 0 libsystem_kernel.dylib 0x00000002478e3cd4 _mach_msg2_trap :8 (in libsystem_kernel.dylib) 1 libsystem_kernel.dylib 0x00000002478e7214 _mach_msg_overwrite :428 (in libsystem_kernel.dylib) 2 libsystem_kernel.dylib 0x00000002478e705c _mach_msg :24 (in libsystem_kernel.dylib) 3 libdispatch.dylib 0x00000001d63ffe84 __dispatch_mach_send_and_wait_for_reply :548 (in libdispatch.dylib) 4 libdispatch.dylib 0x00000001d6400224 _dispatch_mach_send_with_result_and_wait_for_reply :60 (in libdispatch.dylib) 5 libxpc.dylib 0x00000001b2114e04 _xpc_connection_send_message_with_reply_sync :256 (in libxpc.dylib) 6 Foundation 0x000000019b6249f0 ___NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY__ :16 (in Foundation) 7 Foundation 0x000000019c06d1b4 -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] :2100 (in Foundation) 8 CoreFoundation 0x000000019dfcb1cc ____forwarding___ :1072 (in CoreFoundation) 9 CoreFoundation 0x000000019dfd3200 ___forwarding_prep_0___ :96 (in CoreFoundation) 10 AudioSession 0x00000001c77498b0 __ZN4avas6client11SessionCore10HandlePingEv :192 (in AudioSession) 11 AudioSession 0x00000001c77497b0 ____ZN4avas6client11SessionCore12DispatchPingEv_block_invoke :52 (in AudioSession) 12 libdispatch.dylib 0x00000001d63e4adc __dispatch_call_block_and_release :32 (in libdispatch.dylib) 13 libdispatch.dylib 0x00000001d63fe7ec __dispatch_client_callout :16 (in libdispatch.dylib) 14 libdispatch.dylib 0x00000001d63ed468 __dispatch_lane_serial_drain :740 (in libdispatch.dylib) 15 libdispatch.dylib 0x00000001d63edf78 __dispatch_lane_invoke :440 (in libdispatch.dylib) 16 libdispatch.dylib 0x00000001d63f6f48 __dispatch_root_queue_drain :364 (in libdispatch.dylib) 17 libdispatch.dylib 0x00000001d63f6d08 __dispatch_worker_thread :268 (in libdispatch.dylib) 18 libsystem_pthread.dylib 0x00000001f9ff144c __pthread_start :136 (in libsystem_pthread.dylib) 19 libsystem_pthread.dylib 0x00000001f9fed8cc _thread_start :8 (in libsystem_pthread.dylib) Thread 132: 0 libsystem_kernel.dylib 0x00000002478e3cd4 _mach_msg2_trap :8 (in libsystem_kernel.dylib) 1 libsystem_kernel.dylib 0x00000002478e7214 _mach_msg_overwrite :428 (in libsystem_kernel.dylib) 2 libsystem_kernel.dylib 0x00000002478e705c _mach_msg :24 (in libsystem_kernel.dylib) 3 libdispatch.dylib 0x00000001d63ffe84 __dispatch_mach_send_and_wait_for_reply :548 (in libdispatch.dylib) 4 libdispatch.dylib 0x00000001d6400224 _dispatch_mach_send_with_result_and_wait_for_reply :60 (in libdispatch.dylib) 5 libxpc.dylib 0x00000001b2114e04 _xpc_connection_send_message_with_reply_sync :256 (in libxpc.dylib) 6 Foundation 0x000000019b6249f0 ___NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY__ :16 (in Foundation) 7 Foundation 0x000000019c06d1b4 -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] :2100 (in Foundation) 8 CoreFoundation 0x000000019dfcb1cc ____forwarding___ :1072 (in CoreFoundation) 9 CoreFoundation 0x000000019dfd3200 ___forwarding_prep_0___ :96 (in CoreFoundation) 10 AudioSession 0x00000001c7754198 __ZNK4avas6client11SessionCore18SetBatchPropertiesEP12NSDictionaryIP8NSStringPU25objcproto14NSSecureCoding11objc_objectEPU15__autoreleasingP7NSArrayIPS2_IS4_P8NSNumberEENS_30AVAudioSessionBatchSetStrategyEbb :548 (in AudioSession) 11 AudioSession 0x00000001c7753e58 __ZNK4avas6client11SessionCore20SetBatchPropertiesMXEP12NSDictionaryIP8NSStringPU25objcproto14NSSecureCoding11objc_objectE :92 (in AudioSession) 12 AudioSession 0x00000001c775179c __ZN4avas6client11SessionCore11setCategoryEP8NSStringS3_32AVAudioSessionRouteSharingPolicym :472 (in AudioSession) 13 AudioSession 0x00000001c7768f88 -[AVAudioSession setCategory:withOptions:error:] :68 (in AudioSession) 14 AlipayWallet 0x000000010140580c -[AVAudioSession(APMHook) apmhook_setCategory:withOptions:error:] APMHookAudioSession.m:35 (in AlipayWallet) 15 AlipayWallet 0x00000001014001a4 -[APMAudioSessionManager resume] APMAudioSessionManager.m:718 (in AlipayWallet) 16 libdispatch.dylib 0x00000001d63e4adc __dispatch_call_block_and_release :32 (in libdispatch.dylib) 17 libdispatch.dylib 0x00000001d63fe7ec __dispatch_client_callout :16 (in libdispatch.dylib) 18 libdispatch.dylib 0x00000001d63ed468 __dispatch_lane_serial_drain :740 (in libdispatch.dylib) 19 libdispatch.dylib 0x00000001d63edf44 __dispatch_lane_invoke :388 (in libdispatch.dylib) 20 libdispatch.dylib 0x00000001d63f83ec __dispatch_root_queue_drain_deferred_wlh :292 (in libdispatch.dylib) 21 libdispatch.dylib 0x00000001d63f7ce4 __dispatch_workloop_worker_thread :692 (in libdispatch.dylib) 22 libsystem_pthread.dylib 0x00000001f9fee3b8 __pthread_wqthread :292 (in libsystem_pthread.dylib) 23 libsystem_pthread.dylib 0x00000001f9fed8c0 _start_wqthread :8 (in libsystem_pthread.dylib)
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770
Activity
Feb ’26
"Baking together" two audio tracks into one for drag-and-drop
Hi all, with my app ScreenFloat, you can record your screen, along with system- and microphone audio. Those two audio feeds are recorded into separate audio tracks in order to individually remove or edit them later on. Now, these recordings you create with ScreenFloat can be drag-and-dropped to other apps instantly. So far, so good, but some apps, like Slack, or VLC, or even websites like YouTube, do not play back multiple audio tracks, just one. So what I'm trying to do is, on dragging the video recording file out of ScreenFloat, instantly baking together the two individual audio tracks into one, and offering that new file as the drag and drop file, so that all audio is played in the target app. But it's slow. I mean, it's actually quite fast, but for drag and drop, it's slow. My approach is this: "Bake together" the two audio tracks into a one-track m4a audio file using AVMutableAudioMix and AVAssetExportSession Take the video track, add the new audio file as an audio track to it, and render that out using AVAssetExportSession For a quick benchmark, a 3'40'' movie, step 1 takes ~1.7 seconds, and step two adds another ~1.5 seconds, so we're at ~3.2 seconds. That's an eternity for a drag and drop, where the user might cancel if there's no immediate feedback. I could also do it in one step, but then I couldn't use the AV*Passthrough preset, and that makes it take around 32 seconds then, because I assume it touches the video data (which is unnecessary in this case, so I think the two-step approach here is the fastest). So, my question is, is there a faster way? The best idea I can come up with right now is, when initially recording the screen with system- and microphone audio as separate tracks, to also record both of them into a third, muted, "hidden" track I could use later on, basically eliminating the need for step one and just ripping the two single audio tracks out of the movie and only have the video and the "hidden" track (then unmuted), but I'd still have a ~1.5 second delay there. Also, there's the processing and data overhead (basically doubling the movie's audio data). All this would be great for an export operation (where one expects it to take a little time), but for a drag-and-drop operation, it's not ideal. I've discarded the idea of doing a promise file drag, because many apps do not accept those, and I want to keep wide compatibility with all sorts of apps. I'd appreciate any ideas or pointers. Thank you kindly, Matthias
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737
Activity
Mar ’25
AVPlayerViewController crashes
I have a crash related to playing video in AVPlayerViewController and AVQueuePlayer. I download the video locally from the network and then initialize it using AVAsset and AVPlayerItem. Can't reproduce locally, but crashes occur from firebase crashlytics only for users starting with iOS 18.4.0 with this trace: Crashed: com.apple.avkit.playerControllerBackgroundQueue 0 libobjc.A.dylib 0x1458 objc_retain + 16 1 libobjc.A.dylib 0x1458 objc_retain_x0 + 16 2 AVKit 0x12afdc __77-[AVPlayerController currentEnabledAssetTrackForMediaType:completionHandler:]_block_invoke + 108 3 libdispatch.dylib 0x1aac _dispatch_call_block_and_release + 32 4 libdispatch.dylib 0x1b584 _dispatch_client_callout + 16 5 libdispatch.dylib 0x6560 _dispatch_continuation_pop + 596 6 libdispatch.dylib 0x5bd4 _dispatch_async_redirect_invoke + 580 7 libdispatch.dylib 0x13db0 _dispatch_root_queue_drain + 364 8 libdispatch.dylib 0x1454c _dispatch_worker_thread2 + 156 9 libsystem_pthread.dylib 0x4624 _pthread_wqthread + 232 10 libsystem_pthread.dylib 0x19f8 start_wqthread + 8
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2
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3
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263
Activity
May ’25
After iOS 18.5, the AVFoundation AVCaptureSessionInterruptionReason.videoDeviceNotAvailableWithMultipleForegroundApps error has caused a significant increase in camera black screen issues.
Issue: After iOS 18.5 release, our app is experiencing a significant increase in AVCaptureSessionInterruptionReason.videoDeviceNotAvailableWithMultipleForegroundApps errors. Details: Our camera-related code has not been updated recently.However, we've observed that the error rate has significantly increased starting from May 2025. The error rate has risen from approximately 0.02% (2 in 10,000 users) to 0.1% (1 in 1,000 users). This represents a 5x increase in error occurrence. The frequency has increased noticeably since iOS 18.5 This is affecting our app's camera functionality and user experience Questions: Are there any known changes in iOS 18.5 regarding camera access management? What are the recommended best practices to handle this interruption reason? Are there any API changes we should be aware of? Best, Shay
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2
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495
Activity
Oct ’25