Explore the integration of media technologies within your app. Discuss working with audio, video, camera, and other media functionalities.

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Why does CADisplayLink of an external UIScreen drift in time?
I am using Apple's original Lightning Digital AV-adapter (Lightning-to-HDMI dongle) to connect my iPhone to an external display via a HDMI cable. I need to synchronize rendering with the external display's refresh rate, so I create a new CADisplayLink tied to the external display's UIScreen: UIScreen.screens[externalDisplayIdx].displayLink(withTarget:, selector:). The callback is being called regularly, but with increasing delay relative to the CADisplayLink.timestamp, so the next time the callback is called, I have less and less time to draw the next frame (see the snippet below). Assuming 60 FPS, the value of secondsTillDeadline starts at an arbitrary value in the range of approx -0.0001 to 0.0166667, and then it slowly decreases towards zero (and for a brief period it goes into small negative numbers). Once it reaches zero, it flips back to 0.0166667 and continues to decrease again. This cycle repeats indefinitely. Changing the external display's resolution (UIScreen's mode) or the CADisplayLink's preferredFrameRateRange to a lower FPS does not seem to have any effect on the temporal drifting (even the rate of change seem to be the same). When I create a new CADisplayLink for the iPhone's main screen, the value of secondsTillDeadline is stable, it does not drift and it is very close to 0.0166667, as expected. Is this drift caused by the external monitor or by Apple's Lightning-to-HDMI dongle ...or is the problem somewhere else? Can the drifting be stopped? func onDisplayLinkUpdate(displayLink: CADisplayLink) { // Gradually decreases from 0.01667 to -0.0001, then flips back to 0.01667 and continues to decrease let secondsTillDeadline = displayLink.targetTimestamp - CACurrentMediaTime() }
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222
Aug ’25
BackgroundAssets `url(for:` throws error for locally available asset
On an iPhone running iOS 26 beta 5, url(for: FilePath("subdir/asset.mov")) most always throws this error: The URL for “subdir/asset.mov” couldn’t be retrieved: “asset.mov” couldn’t be copied to “subdir” because an item with the same name already exists. Yet, contents(at: FilePath("subdir/asset.mov")) always returns Data for a playable AVMovie. How can I avoid this url(for:) error? The asset pack in question is downloaded. The error persists even after pack deletion, redownload, relaunch, and combinations of that. // Assets repo root subdir.aar subdir/asset.mov subdir/asset_thumb.heic subdir/Manifest.json // Manifest.json { "assetPackID": "subdir", "downloadPolicy": { "onDemand": {} }, "fileSelectors": [ { "directory": "subdir", }, ], "platforms": [ "iOS", "visionOS" ] } xcrun ba-package subdir/Manifest.json -o subdir.aar xcrun ba-serve --host 192.168.0.10 -p 443 subdir.aar
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173
Aug ’25
Metal CIKernel instances with arbitrarily structured data arguments
Hi, In the iOS13 and macOS Catalina release notes it says: Metal CIKernel instances now support arguments with arbitrarily structured data. I've been trying to use this functionality in a CIKernel with mixed results. I'm particularly interested in passing data in the form of a dynamically sized array. It seems to work up to a certain size. Beyond the threshold excessive data is discarded and the kernel becomes unstable. I assume there is some kind of memory alignment issue going on, but I've tried various types in my array and always get a similar result. I have not found any documentation or sample code regarding this. It would be great to know how this is intended to work and what the limitations are. In the forums there are two similar unanswered questions about data arguments, so I'm sure there are a few out there with similar issues. Thanks! Michael
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412
Oct ’25
How to detect a song end?
I'm playing library items (MPMediaItem) and apple music tracks (Track) in MPMusicPlayerApplicationController.applicationQueuePlayer, but I can't use the actual Queue functionality because I can't figure out how to get both media types into the same queue. If there's a way to get both types in a single queue, that would solve my problem, but I've given up on that one. Because I can't use a queue, I have to be able to detect when a song ends so that I can put the next song in the queue and play it. The only way I can figure out to detect when a song ends is by watching the playBackState, and I've actually got that pretty much working, but it's really ugly, because you get playBackState of paused when a song ends, and when a bluetooth speaker disconnects, etc. The only answer I've been able to find on the internet is to watch the MPMusicPlayerControllerNowPlayingItemDidChange, and when that fires, and the nowPlayingItem is NIL, a song ends.. but that's not the case. When a song ends, the nowPlayingItem remains the same. There's got to be an answer to this problem, right?
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5.3k
Jan ’25
MusicKit in playgrounds not supported?
Has anyone been able to successfully use MusicCatalogSearchRequest in a playgrounds app? I have configured my playground similar to a regular app: app id with automatic music token generation turned on, music access authorized within the app itself, but whenever I query MusicCatalogSearchRequest I get an error thrown with .developerTokenRequestFailed. Considering musickit is restricted in the sim, it would not surprise me if it was the same in playgrounds but it would be super helpful if I could prototype with musickit in playgrounds 4!
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1.3k
Apr ’25
MusicKit swift start / end times
Hello! I am having trouble setting start times for songs when using the ApplicationMusicPlayer. When I initialize a new MusicPlayer.Queue.Entry using the following constructor, I am seeing strange results: init( _ playableMusicItem: PlayableMusicItem, startTime: TimeInterval? = nil, endTime: TimeInterval? = nil ) It appears that any value I provide for startTime is also applied to the endTime. For example: MusicPlayer.Queue.Entry(playable, startTime: TimeInterval(30), endTime: TimeInterval(183)) provides the following console output: MusicPlayer.Queue.Entry(id: "3D6A3DA3-595E-4657-8DBA-DDD245BBB7EF", transientItem: PlayableMusicItem, startTime: 30.0, endTime: 30.0) I have also tried setting the endTime to nil with the same result. Does anyone have any experience setting start times for songs using the MusicKit ApplicationMusicPlayer? Any feedback is greatly appreciated!
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1.9k
Dec ’24
ScreenCaptureKit and mixed Retina/non-Retina configuration
The two ScreenCaptureKit WWDC22 sessions show how to capture with the new framework but the retina factor is hardcoded to 2 in SCStreamConfiguration. When using on a non-retina display, the screencapture is floating on the upper-left corner of the image buffer. There does not seem to be a simple way to retrieve the retina factor from the SCShareableContent data (when configuring the capture). When processing the streaming output, the SCStreamFrameInfo attachment is supposed to have a scaleFactor property but .scaleFactor does not return a value. I have found out that the attachement dictionary contains SCStreamUpdateFrameDisplayResolution. This entry gives me the retina factor but it is not an official SCStreamFrameInfo key. I list the keys to access it. What is the proper way with ScreenCapture to handle the retina factors ?
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801
Jun ’25
EXIF Makernote no read in Ventura
I have a custom app running on a Mac Studio with Ventura that grabs a snapshot image from a network camera. It then adds some extra information into the EXIF "MakerNote" field. However the metadata cannot be read back out of the image when running Ventrua, it can however be read out of the same image file on a Mac that is not running Ventura. It would appear Apple has removed support for reading MakerNote in Ventura but still supports writing MakerNote in Ventura. This code is about 7 years old and written in ObjC and has worked with no issue until Ventura came along. Calls used CGImageDestinationAddImageFromSource(); // used to write the image to disk with the extra metadata - Works on Ventura CGImageSourceCopyPropertiesAtIndex(); // used to read the meta data from an image - does not return "MakeNote" data Is there a new way to read EXIF "MakeNote" data from image files that was introduced with Ventura?
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922
Nov ’24
Terrible performance when using MusicKit's Artwork with UIKit
I'm building a UIKit app that reads user's Apple Music library and displays it. In MusicKit there is the Artwork structure which I need to use to display artwork images in the app. Since I'm not using SwiftUI I cannot use the ArtworkImage view that is recommended way of displaying those images but the Artwork structure has a method that returns url for the image which can be used to read the image. The way I have it setup is really simple: extension MusicKit.Song { func imageURL(for cgSize: CGSize) -> URL? { return artwork?.url( width: Int(cgSize.width), height: Int(cgSize.height) ) } func localImage(for cgSize: CGSize) -> UIImage? { guard let url = imageURL(for: cgSize), url.scheme == "musicKit", let data = try? Data(contentsOf: url) else { return nil } return .init(data: data) } } Now, everytime I access .artwork property (so a lot of times) the main thread gets blocked and the console output gets bombared with messages like these: 2023-07-26 11:49:47.317195+0200 Plum[998:297199] [Artwork] Failed to create color analysis for artwork: <MPMediaLibraryArtwork: 0x289591590> with error; Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named com.apple.mediaartworkd.xpc was invalidated: failed at lookup with error 159 - Sandbox restriction." UserInfo={NSDebugDescription=The connection to service named com.apple.mediaartworkd.xpc was invalidated: failed at lookup with error 159 - Sandbox restriction.} 2023-07-26 11:49:47.317262+0200 Plum[998:297199] [Artwork] Failed to create color analysis for artwork: file:///var/mobile/Media/iTunes_Control/iTunes/Artwork/Originals/4b/48d7b8d349d2de858413ae4561b6ba1b294dc7 2023-07-26 11:49:47.323099+0200 Plum[998:297013] [Plum] IIOImageWriteSession:121: cannot create: '/var/mobile/Media/iTunes_Control/iTunes/Artwork/Caches/320x320/4b/48d7b8d349d2de858413ae4561b6ba1b294dc7.sb-f9c7943d-6ciLNp'error = 1 (Operation not permitted) My guess is that the most performance-heavy task here is performing the color analysis for each artwork but IMO the property backgroundColor should not be a stored property if that's the case. I am not planning to use it anywhere and if so it should be a computed async property so it doesn't block the caller. I know I can move the call to a background thread and that fixes the issue of blocking main thread but still the loading times for each artwork are terribly slow and that impacts the UX. SwiftUI's ArtworkImage loads the artworks much quicker and without the errors so there must be a better way to do it.
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1.5k
Mar ’25
HDR10 MVHECV can not play on Safari
Hi, just generated a HDR10 MVHEVC file, mediainfo is below: Color range : Limited Color primaries : BT.2020 Transfer characteristics : PQ Matrix coefficients : BT.2020 non-constant Codec configuration box : hvcC+lhvC then generate the segment files with below command: mediafilesegmenter --iso-fragmented -t 4 -f av_1 av_new_1.mov then upload the segment files and prog_index.m3u8 to web server. just find that can not play the HLS stream on Safari... the url is http://ip/vod/prog_index.m3u8 just checked that if i remove the tag Transfer characteristics : PQ when generating the MVHEVC file. above same mediafilesegmenter command and upload the files to web server. the new version of HLS stream is can play on Safari... Is there any way to play HLS PQ video on Safari. thanks.
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782
Feb ’25
How to detect the end of playback with the system music player?
Since iOS 12 it has become difficult to detect the end of playback using the system music player. In earlier iOS versions, the now playing item would be set nil and you would receive a notification that the player stopped. In iOS 12 and later, nowPlayingItem still contains the current song and the only notification you get is MPMusicPlayerControllerPlaybackStateDidChangeNotification with the playbackState set to MPMusicPlaybackStatePaused. Pressing pause in my car (or any remote access) generates the same conditions making it difficult to correctly detect the difference. It would be nice if they added a notification that playback was done (similar to the other players). Any suggestions?
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753
Mar ’25
MusicKit and sorted artist and album names?
I have an app that gets data from Music.app with both the iTunesLibrary and MusicKit. iTunesLibrary has ITLibArtist.sortName and ITLibAlbum.sortTitle and ITLibAlbum.sortAlbumArtist. I can’t seem to find an equivalent in MusicKit. How are those properties obtained using MusicKit? Thanks. FYI I have filed FB15554956 on this. You also may see my code at https://github.com/bolsinga/itunes_json
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503
Nov ’24
Playlist IDs from MusicKit not working with Apple Music API
I am building an app for MacOS and I am trying to implement the code to add songs to a library playlist (which is added below). The issue I am having is that if I use Music Kit to load a users library playlists, the ID for the playlist (which is just a string of numbers) does not work with the Add tracks to a Library Playlist endpoint of Apple Music API. If I retrieve the playlists from the Apple Music API and use that playlist ID (which is different than the id I get from MusicKit) my code works fine and adds the song to the playlist. The problem is that when getting a users library playlists from Apple Music API is that it does not give me all of the library playlists that I get when using Music Kit and it also does not give me Artwork for playlists that have the collage of album covers, so I would prefer to use Music Kit to get the playlists. I have also tested trying to retrieve a single playlist using the Apple Music API with the playlist Id from Music Kit and it does not work. I get the error that the resource cannot be found. Since this is a macOs app I cannot use MusicKit to add songs to library playlists. Does anyone know a way to resolve this? Or a possible workaround? Ideally I want to use MusicKit to get the library playlists and have some way to use the playlist Id and add songs to that playlist. Below is my code for adding a song to a playlist using the Apple Music API, which works correctly only if I originally get the library playlist's id value from a playlist retrieved from the Apple Music API. Also, does anyone know why the playlist Id's are not universal and are different when using Music Kit and Apple Music API? For songs and tracks it does not seem to matter if I use music kit or Apple Music API, the Id's are in the correct format for Apple Music API to use and work with my code. Thanks everyone for any and all help! func addToPlaylist(songs: [Track], playlist: Playlist, alert: Binding<AlertItem?>) async { let tracks = AppleMusicPlaylistPostRequestBody(data: songs.compactMap { AppleMusicPlaylistPostRequestItem(id: $0.id.rawValue, type: "songs") // or "library-songs" }) let playlistID = playlist.id // Build the request URL for adding a song to a playlist guard let url = URL(string: "https://api.music.apple.com/v1/me/library/playlists/\(playlistID)/tracks") else { alert.wrappedValue = AlertItem(title: "Error", message: "Invalid URL for the playlist.") return } // Authorization Header guard let musicUserToken = try? await MusicUserTokenProvider().getUserMusicToken() else { alert.wrappedValue = AlertItem(title: "Error", message: "Unable to retrieve Music User Token.") return } do { var request = URLRequest(url: url) request.httpMethod = "POST" request.setValue("Bearer \(musicUserToken)", forHTTPHeaderField: "Authorization") request.setValue("application/json", forHTTPHeaderField: "Content-Type") let encoder = JSONEncoder() let data = try encoder.encode(tracks) request.httpBody = data let musicRequest = MusicDataRequest(urlRequest: request) let musicRequestResponse = try await musicRequest.response() // Check if the request was successful (status 201) if musicRequestResponse.urlResponse.statusCode == 201 { alert.wrappedValue = AlertItem(title: "Success", message: "Song successfully added to the playlist.") } else { print("Status Code: \(musicRequestResponse.urlResponse.statusCode)") print("Response Data: \(String(data: musicRequestResponse.data, encoding: .utf8) ?? "No Data")") // Attempt to decode the error response into the AppleMusicErrorResponse model if let appleMusicError = try? JSONDecoder().decode(AppleMusicErrorResponse.self, from: musicRequestResponse.data) { let errorMessage = appleMusicError.errors.first?.detail ?? "Unknown error occurred." alert.wrappedValue = AlertItem(title: "Error", message: errorMessage) } else { alert.wrappedValue = AlertItem(title: "Error", message: "Failed to add song to the playlist.") } } } catch { alert.wrappedValue = AlertItem(title: "Error", message: "Network error: \(error.localizedDescription)") } }
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770
Dec ’24
Apple music feed Parquet download urls
https://api.media.apple.com/v1/feed/exports/song_2024-11-02T16-02/parts?limit=200&offset=400 This is the api used to get parquet file urls. I need all the urls in one api hit, right now if I don't provide the limit then default it is taking 100 and max is 200. How to get all the records in one hit? Or the count of parquet records in one hit?
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515
Nov ’24
How can I add support for Apple Music lyrics sharing in my app?
I noticed that Instagram and iMessage support receiving shared lyrics from Apple Music. Specifically, when users long-press lyrics, a sheet pops up showing iMessage and Instagram. Clicking on either app generates a beautifully formatted lyrics image. I've looked through MusicKit documentation but couldn't find any related APIs. How can I implement this functionality in my app?
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414
Feb ’25
How to Implement Screen Mirroring in iOS for Google TV?
I am developing an iOS application that supports screen mirroring to Google TV (or Chromecast with Google TV). My goal is to mirror the iPhone/iPad screen in real time to a Google TV device. What I Have Tried So Far I have explored multiple approaches but haven't found a direct way to achieve low-latency screen mirroring. Here are some of my findings: Google Cast SDK: Google Cast SDK is primarily designed for casting media (videos, images, audio) rather than real-time mirroring. It supports custom receiver applications, but there are no direct APIs for full screen mirroring. Casting a recorded video is possible, but it introduces latency and is not real-time. ReplayKit for Screen Capture: RPScreenRecorder.shared().startCapture(handler: ...) allows capturing the iPhone screen as a video stream. However, sending this stream to Google TV in real time is a challenge. I could potentially encode the video as HLS and stream it, but the delay is significant. RTSP/UDP Streaming: Some third-party libraries support RTSP/UDP streaming for real-time screen sharing. Google TV does not natively support RTSP, making this approach difficult. My Questions: Is it possible to achieve real-time screen mirroring on Google TV using Google Cast SDK? Does Google TV support WebRTC or any low-latency streaming protocol that can be used from iOS? Are there any alternative approaches to mirror an iOS screen to Google TV with minimal latency? I would appreciate any guidance, code examples, or references to relevant documentation.
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437
Feb ’25
How Does iPhone 15+ (USB-C) Support UVC Devices? Is MFi Certification Required?
In the past, when using Lightning, many external devices had to go through MFi certification. However, since the iPhone 15 switched from Lightning to USB-C, is MFi certification still required? Our company has developed several UVC devices, and we have confirmed that iPads can read frames from external cameras through the external device type in AVFoundation. However, this is not supported on iPhones. We are currently exploring feasible ways to enable UVC device support on iPhones. Is MFi certification the only option? If so, is the MFi certification process for USB-C the same as it was for Lightning? Does it still require purchasing an MFi chip and manufacturing specially designed USB-C cables?
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197
Mar ’25
MusicKit for Android reports an error when playing stations
When I use musicKit SDK for Android 1.1.2, I found that MediaContainerType only defines three types: NONE = 0; ALBUM = 1; PLAYLIST = 2; The RADIO_STATION type is not defined. However, the documentation of com.apple.android.music.playback.model states that the RADIO_STATION type is supported. This problem causes an error after I pass in the stations ID: MediaSessionManager com.apple.android.music.sdk.testapp D onPlaybackError() Quincy java.io.IOException May I ask how to solve this problem?
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69
Apr ’25
MusicKit for Android reports an error when playing stations
我在使用 musicKit SDK for Android 1.1.2 时,发现 MediaContainerType 只定义了三种类型: 无 = 0; 专辑 = 1; 播放列表 = 2; 未定义 RADIO_STATION 类型。 但是,com.apple.android.music.playback.model 的文档指出支持 RADIO_STATION 类型。 此问题在我传入 stations ID 后会导致错误: MediaSessionManager com.apple.android.music.sdk.testapp D onPlaybackError() Quincy java.io.IOException 请问如何解决这个问题?
1
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53
May ’25