I have a driver extending IOUserUSBSerial and I want the device to show up as /dev/tty.mycustombasename-123 and /dev/cu. respectively. How can I achieve that?

Hi Everyone, We are currently migrating a mature legacy KEXT to DriverKit for our PCIe SCSI storage controller (connected via Thunderbolt 3). During the DEXT load sequence, we have observed that the system automatically triggers a power state transition from State 0 (Off) to State 2 (On). However, this process results in a Kernel Panic due to a timeout after approximately 21 seconds. We have verified that our implementation of Start_Impl, UserInitializeController_Impl, and SetPowerState_Impl executes extremely fast, with a total execution time of less than one second. Specifically, SetPowerState_Impl returns kIOReturnSuccess immediately upon being called. Furthermore, our current Info.plist does not contain any IOPowerManagement dictionary or related keys. Despite the fast execution and the absence of explicit power management declarations in the plist, the kernel power management state machine (IOServicePM) still generates a 21-second timeout, leading to the following panic: Panic Log: panic(cpu 7 caller 0xfffffe0020be8fec): MySCSIDriver::setPowerState(0xfffffe2fb1a65c00 : 0xfffffe0020bfed88, 0 -> 2) timed out after 21257 ms @IOServicePM.cpp:5609 com.example.driver.dext: ( id: com.example.driver.dext; path: /Library/SystemExtensions/[UUID]/com.example.driver.dext; state: loaded ) Note on Previous Discussion: I would like to express my gratitude to Kevin from Apple DTS for the helpful discussion regarding the implementation of BundleParallelTask on the forums. Since then, we have shifted our development focus toward completing the overall management ecosystem, delivering a comprehensive operational interface for users, and handling specific user environments and behaviors. Our current priority is ensuring system stability—specifically resolving these Thunderbolt-related power management issues (sleep/wake)—to prepare the product for upcoming testing. I remain very grateful for the guidance provided on batch task optimization and intend to resume those optimizations once this critical stability baseline is secured. Technical Guidance Needed for PM Migration In our legacy KEXT, we utilized PMinit(), registerPowerDriver(), and joinPMtree() to precisely control the timing of power management registration. In transitioning to the DriverKit SDK, we have not found clear guidance on several key points: Standardized Migration Path: What is the recommended way to implement equivalent power management initialization (formerly PMinit) within a DriverKit subclass? In DriverKit, how should we replicate the behavior of manually calling registerPowerDriver and joinPMtree to ensure the driver is only monitored once the hardware is ready? Implicit Power Registration: Why does the system enforce a setPowerState(0 -> 2) transition on a subclass of IOUserSCSIParallelInterfaceController even when no IOPowerManagement dictionary is defined in the Info.plist? Is this a default behavior of the SCSI or PCI transport framework? Thunderbolt Specifics: Are there specific power proxying requirements or configurations for PCIe devices over Thunderbolt to avoid conflicts with the default IOPCIFamily power policies? Best Regards, Charles

While I welcome the arrival of a userspace implementation of drivers, DriverKit as it stands has some notable flaws. My main concern is the ability of open-source projects like HoRNDIS being able to access paid developer accounts and the limited entitlement scope (plus the waiting period) for what is essentially a hobbyist free project. Even if the developer is a professional company, some legacy hardware will go unsupported because of a lack of support from the vendor. Providing a way for users who need access to older hardware would be needed. Three concrete requests: A class-level or wildcard VID/PID entitlement for open source projects with a verifiable public repository A free or reduced-cost entitlement path for non-commercial volunteer-maintained drivers Published approval criteria and timelines so projects can plan accordingly Depreciating kexts without providing an accessible successor for community projects isn't security, it is gatekeeping access to hardware that is critically needed. Is this use case on the roadmap at all? Developers deserve a clear answer.

Hi everyone, I observed a behavior with AirPrint from an iPhone and wanted to confirm if this is expected behavior from iOS. Scenario tested: File type: Photo Print-quality selected by the user: Normal Observation (from packet capture): When checking the PCAP for the request sent from the iPhone, the print-quality attribute is always sent as high, even though the user selected Normal in the UI. Question: Is this an expected behavior in iOS/AirPrint where photos are always sent with print-quality=high regardless of the user-selected print quality? Or could this be a bug?

I have a custom hardware board that I want to communicate serially with from an iPad. Should I use the DriverKit route or the MFi route?

I have two Macbook Pros: 14" M4 Pro (company) 16" M4 Max (personal) I work remote full-time and recently purchased 2 of the new Studio Display XDRs. Everything works perfectly however I chose to connect them to the M4 Max. I have a caldigit Element TB5 hub and can daisy chain both monitors through that perfectly. With that said, no matter how I plug them into the M4 Pro I can only ever get one to light up at a time. What I have tried to resolve it: Plug them in individually to the m4 pro Plug them in one at a time, force them to 60hz and then plug them both in. Daisy Chaining the displays Daisy Chaining the displays through the TB5 Hub Nothing works. Only one display comes on and its whichever is plugged in first. I have even tried lowering the refresh to as low as it goes on both manually then plugging them back in. Still nothing. From what I am reading it appears to be that the M4 Pro has 3 display lanes and when I plug the first studio display XDR it is using 2 lanes. If I go down to 60hz which is what the original studio display was, then it should theoretically go down to 1 display lane allowing a second to be plugged in. A bunch of people had the older studio display running 2x 5k ASD monitors on the M4 Pro. Now with the latest Studio Display XDR I am stuck. I was researching possibly editing the EDID of each to mimic the older studio display, but I don't know how to do that easily without BetterDisplay and right now I have no ability to install that. There is a chance I can get approval to run commands / BetterDisplay to get this working if a solution can be found. What I think the ultimate fix is for the firmware / macOS to realize the limitation, force the studio display XDR to 60hz when a second monitor is plugged in and they both would work. A single Studio Display XDR could run 120hz, but immediately upon plugging a second one it swaps to 60hz. I am completely fine with that scenario. I have found a few discussions about this topic with the main one being on apple discussions: https://discussions.apple.com/thread/256262701?sortBy=rank&answerId=261888577022 Someone sort of gave me this idea on Mac because they were trying to use the studio display XDR on windows and it appears to have worked with cloning an older ASD EDID on the new model: https://www.reddit.com/r/mac/comments/1s3ani5/got_studio_display_xdr_working_on_windows_pc_5k/ I don't really know what else to do. I opened a ticket with support. Case # 102853480566, but it went no where. I got disconnected during the first call after describing everything and when they reached back out they didn't even give me 2 seconds to pick up and they hung up and closed the ticket. I really don't want to return the displays because they are beautiful and work beautifully on the m4 max. They should work with 60hz on the m4 pro. Who / How / When can we get this resolved? I would be happy to work with an Apple dev / engineer to help resolve this.

Hello, I have crated a DriverKit driver for macOS and iPad M-series if I ever get the mac driver working. I have the correct entittlements, and matching provisioning profile downloaded manually. The driver loads (no errors!), and is visible in ioreg below the usb device (when plugged). The issue is that I never get any log from the driver, have reduced to minimal working code (below). When I debug with lldb, I load the symbols for my driver and break on init and Start - but lldb never triggers == never calls start or init. This is also why no logs. When I unplug the device, the driver process (ps aux) keeps running, causes a hard crash of the Mac with dext remove/or kill driver.dext process. I have asked Claude - but its just running in circles: check Info.plist=ok, check entitlements=ok, check code (minimal)=ok, check iig=ok, check provisioning profile=ok, check build settings=ok, check ioreg=ok, check code signature=ok, start over I don't get any log from my driver, which is consistent with init() not being called. All logs from kernel & friends (AMFI) do show the driver loading - no errors. Any tips appreciated! // USBDriver.iig #ifndef USBDriver_h #define USBDriver_h #include <USBDriverKit/IOUSBHostInterface.iig> class USBDriver: public IOService { public: virtual bool init() override; virtual void free() override; virtual kern_return_t Start(IOService * provider) override; virtual kern_return_t Stop(IOService * provider) override; }; // USBDriver.cpp #include <os/log.h> #include <DriverKit/DriverKit.h> #include "USBDriver.h" bool USBDriver::init() { if (!super::init()) return false; os_log(OS_LOG_DEFAULT, "terminal.driver: init()"); return true; } kern_return_t IMPL(USBDriver, Start) { os_log(OS_LOG_DEFAULT, "terminal.driver: Start()"); kern_return_t ret = super::Start(provider); if (ret != kIOReturnSuccess) { os_log(OS_LOG_DEFAULT, "terminal.driver: super::Start failed: 0x%08x", ret); return ret; } os_log(OS_LOG_DEFAULT, "terminal.driver: Start() success"); return super::Start(provider); } kern_return_t IMPL(USBDriver, Stop) { os_log(OS_LOG_DEFAULT, "terminal.driver: Stop()"); return super::Stop(provider); } void USBDriver::free() { os_log(OS_LOG_DEFAULT, "terminal.driver: free()"); super::free(); }

I might be trying to achieve the impossible here, but if there's another way to go about it any advice would be appreciated. I've got an older Linux application that reflashes firmware on a connected USB HID device that I'm trying to port to macOS. Essentially the device starts as an HID interface (0x03/0x01/0x01) but to update firmware receives a simple control payload and then restarts and connects as a different (non-HID) device. However I can't open the HID device at all, I'm guessing this is some sort of permission error (SIP?). AppleUSBHostUserClient::openGated: failed to open IOUSBHostDevice... provider is already opened for exclusive access by AppleUSB20Hub hid_open_path: failed to open IOHIDDevice from mach entry: (0xE00002E2) not permitted AppleUSBXHCICommandRing::setAddress: completed with result code 4 AppleUSBHostPort::createDevice: failed to create device (0xe00002bc) AppleUSBIORequest ... transaction error ... 0xe00002ed Is there any way at all to do this on macOS? Interestingly if you run a Windows VM in VMWare or similar and connect the device to that VM it works, so there's obviously some way but I'd like to create a simple standalone tool.

I am developing a USB MTP device for use with macOS. When the device is connected while Preview is running, I observe the host send OpenSession, then GetDeviceInfo, and then no further MTP commands. I do not see a later CloseSession. Problem is that once this happens, exclusive access to the USB interface is retained, so another application cannot connect to the device. From the device side, there is no obvious way to recover except forcing a USB disconnect/reset or shutting down the USB interface. My questions are: Is this expected behavior for Preview, or for a Preview-related macOS helper? Is it expected on macOS that a client may open an MTP session and then leave it idle without sending CloseSession? I am mainly trying to understand whether this is expected macOS behavior, or whether this should be considered a bug.

How does VMWare access USB devices without have any specifics of the USB device? Does it use the same profile/entitlement process or does it take a different approach?

We are looking for a solution (API, Frameworks) that would allow us to block any type of external device, including storage devices, HIDs, network adapters, and Bluetooth devices according with dynamic rules that comes from management server . This feature is important for endpoint security solutions vendors, and it can be implemented on other platforms and older versions of macOS using the IOKit framework and kexts. I have found one solution that can control the usage only of "storage" devices with the EndpointSecurity framework in conjunction with the DiskArbitration framework. This involves monitoring the MOUNT and OPEN events for /dev/disk files, checking for devices as they appear, and ejecting them if they need to be blocked.. Also, I have found the ES_EVENT_TYPE_AUTH_IOKIT_OPEN event in EndpointSecurity.framework, but it doesn't seem to be useful, at least not for my purposes, because ES doesn't provide AUTH events for some system daemons, such as configd (it only provides NOTIFY events). Furthermore, there are other ways to communicate with devices and their drivers apart from IOKit. DriverKit.framework does not provide the necessary functionality either, as it requires specific entitlements that are only available to certain vendors and devices. Therefore, it cannot be used to create universal drivers for all devices, which should be blocked. Any advice would be greatly appreciated!

I am trying to add a few properties to an IOUSBHostDevice but the SetProperties is returning kIOReturnUnsupported. The reason I am trying to modify the IOUSBHostDevice's properties is so we can support a MacBook Air SuperDrive when it is attached to our docking station devices. The MacBook Air SuperDrive needs a high powered port to run and this driver will help the OS realize that our dock can support it. I see that the documentation for SetProperties says: The default implementation of this method returns kIOReturnUnsupported. You can override this method and use it to modify the set of properties and values as needed. The changes you make apply only to the current service. Do I need to override IOUSBHostDevice? This is my current Start implementation (you can also see if in the Xcode project): kern_return_t IMPL(MyUserUSBHostDriver, Start) { kern_return_t ret = kIOReturnSuccess; OSDictionary * prop = NULL; OSDictionary * mergeProperties = NULL; bool success = true; os_log(OS_LOG_DEFAULT, "&gt; %s", __FUNCTION__); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = Start(provider, SUPERDISPATCH); __Require(kIOReturnSuccess == ret, Exit); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ivars-&gt;host = OSDynamicCast(IOUSBHostDevice, provider); __Require_Action(NULL != ivars-&gt;host, Exit, ret = kIOReturnNoDevice); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = ivars-&gt;host-&gt;Open(this, 0, 0); __Require(kIOReturnSuccess == ret, Exit); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = CopyProperties(&amp;prop); __Require(kIOReturnSuccess == ret, Exit); __Require_Action(NULL != prop, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); mergeProperties = OSDynamicCast(OSDictionary, prop-&gt;getObject("IOProviderMergeProperties")); mergeProperties-&gt;retain(); __Require_Action(NULL != mergeProperties, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); OSSafeReleaseNULL(prop); ret = ivars-&gt;host-&gt;CopyProperties(&amp;prop); __Require(kIOReturnSuccess == ret, Exit); __Require_Action(NULL != prop, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); os_log(OS_LOG_DEFAULT, "%s : %s", "USB Product Name", ((OSString *) prop-&gt;getObject("USB Product Name"))-&gt;getCStringNoCopy()); os_log(OS_LOG_DEFAULT, "%s : %s", "USB Vendor Name", ((OSString *) prop-&gt;getObject("USB Vendor Name"))-&gt;getCStringNoCopy()); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); success = prop-&gt;merge(mergeProperties); __Require_Action(success, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = ivars-&gt;host-&gt;SetProperties(prop); // this is no working __Require(kIOReturnSuccess == ret, Exit); Exit: OSSafeReleaseNULL(mergeProperties); OSSafeReleaseNULL(prop); os_log(OS_LOG_DEFAULT, "err ref %d", kIOReturnUnsupported); os_log(OS_LOG_DEFAULT, "&lt; %s %d", __FUNCTION__, ret); return ret; }

Trying to use IOLog to print out a message from a dext. When I try to use IOLog, I get , though I did not or thought I did not tag it as private. I have tried to update the info.plist file for the dext according to https://developer.apple.com/forums/thread/705810, but that has not helped, or perhaps I am not defining it correctly since it's a dext. Anyone else had this issue, and how did you fix it?

Hello every one good day :) My project uses a mouse driver handling all events from the mouse produced by our company. In the past the driver is a kext, which implement acceleration by HIDPointerAccelerationTable, we prepare data in the driver's info.plist, while our app specifies a value to IOHIDSystem with key kIOHIDPointerAccelerationKey, the driver will call copyAccelerationTable() to lookup the HIDPointerAccelerationTable and return a value. In current DriverKit area, the process above is deprecated. Now I don't know to do. I've read some document: https://developer.apple.com/documentation/hiddriverkit/iohidpointereventoptions/kiohidpointereventoptionsnoacceleration?changes=__7_8 https://developer.apple.com/documentation/hiddriverkit/kiohidmouseaccelerationtypekey?changes=__7_8 https://developer.apple.com/documentation/hiddriverkit/kiohidpointeraccelerationkey?changes=__7_8 but no any description in those articles. Please help!

We’re looking for a reliable way to determine whether an iPad device supports DriverKit. Since there doesn't appear to be a direct public API for this, our current approach is as follows: Retrieve the device’s model identifier (e.g., "iPad14,8") and the iOS/iPadOS version. Map the model identifier to a known iPad model and its associated chip. If the device has an M-series chip, we assume it supports DriverKit. For future-proofing, we plan to assume that any future iPad with a model identifier of iPad15,* or higher will contain an M-series chip and therefore support DriverKit. We have a couple of questions: Is there a more reliable or official API to determine the chip version or DriverKit support? Is it reasonable to rely on the assumptions outlined in steps 2 and 3 for determining DriverKit compatibility?

Hi everyone, I was following the Video Modernize PCI and SCSI drivers with DriverKit and the Document to implement UserMapHBAData(), and here’s my current implementation: // kern_return_t DRV_MAIN_CLASS_NAME::UserMapHBAData_Impl(uint32_t *uniqueTaskID) kern_return_t IMPL(DRV_MAIN_CLASS_NAME, UserMapHBAData) { Log("UserMapHBAData() - Start"); // Define the vm_page_size explicitly const uint32_t vm_page_size = 4096; kern_return_t ret; IOBufferMemoryDescriptor *buffer = nullptr; IOMemoryMap *memMap = nullptr; void *taskData = nullptr; // Create a buffer for HBA-specific task data ret = IOBufferMemoryDescriptor::Create(kIOMemoryDirectionOutIn, ivars->fTaskDataSize, vm_page_size, &buffer); __Require((kIOReturnSuccess == ret), Exit); // Map memory to the driver extension's memory space ret = buffer->CreateMapping(0, 0, 0, 0, 0, &memMap); __Require((kIOReturnSuccess == ret), Exit); // Retrieve mapped memory address taskData = reinterpret_cast<void *>(memMap->GetAddress()); __Require(taskData, Exit); // WARNING: Potential leak of an object stored into 'buffer' // WARNING: Potential leak of an object stored into 'memMap' // Assign a unique task ID ivars->fTaskID++; // ERROR: No member named 'fTaskID' in 'DriverKitAcxxx_IVars' ivars->fTaskArray[ivars->fTaskID] = taskData; *uniqueTaskID = ivars->fTaskID; Log("UserMapHBAData() - End"); return kIOReturnSuccess; Exit: // Cleanup in case of failure if (memMap) { memMap->free(); // Correct method for releasing memory maps } if (buffer) { buffer->free(); // Correct method for releasing buffer memory } LogErr("ret = 0x%0x", ret); Log("UserMapHBAData() - End"); return ret; } For reference, in KEXT, memory allocation is typically done using: IOBufferMemoryDescriptor *buffer = IOBufferMemoryDescriptor::inTaskWithOptions( kernel_task, // Task in which memory is allocated kIODirectionOutIn, // Direction (read/write) 1024, // Size of the buffer in bytes 4); // Alignment requirements However, after installing the dext, macOS hangs, and I have to do a hardware reset. After rebooting, the sysctl list output shows: % sectl list 1 extension(s) --- com.apple.system_extension.driver_extension enabled active teamID bundleID (version) name [state] * - com.accusys.DriverKitAcxxx (5.0/11) com.accusys.DriverKitAcxxx [activated waiting for user] Questions: What could be causing macOS to halt? How should I approach debugging and resolving this issue? Looking forward to your insights, any suggestions would be greatly appreciated! Best regards, Charles

I have reference some related post for this issue: https://developer.apple.com/documentation/xcode-release-notes/xcode-16-release-notes#Foundation https://developer.apple.com/forums/thread/762711 Unfortunately, I'm facing the similar issues even though using Xcode Version 16.2 (16C5032a). we have the following build environment: Xcode version: Xcode 16.2 (16C5032a) macOS Version: macOS 14.7.4 (23H420) Everything builds and install fine. But when attempting to plug on Device on macOS 14.7.4 it crashes immediately with what appears to be a missing Foundation symbol. Crashed Thread: 0 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: Namespace DYLD, Code 4 Symbol missing Symbol not found: __ZThn48_N21IOUserNetworkEthernet25registerEthernetInterfaceE10ether_addrPP24IOUserNetworkPacketQueuejP29IOUserNetworkPacketBufferPoolS5_ Referenced from: &lt;ECE57ABF-0633-3C3B-8427-FB25CC706343&gt; /Library/SystemExtensions/*/com.asix.dext.pciedevice Expected in: &lt;CDEB3490-B1E0-3D60-80CE-59C0682A4B03&gt; /System/DriverKit/System/Library/Frameworks/NetworkingDriverKit.framework/NetworkingDriverKit (terminated at launch; ignore backtrace) Thread 0 Crashed: 0 dyld 0x1041da4c8 __abort_with_payload + 8 1 dyld 0x1041e50cc abort_with_payload_wrapper_internal + 104 2 dyld 0x1041e5100 abort_with_payload + 16 3 dyld 0x1041767f0 dyld4::halt(char const*, dyld4::StructuredError const*) + 304 4 dyld 0x1041732ec dyld4::prepare(dyld4::APIs&amp;, dyld3::MachOAnalyzer const*) + 3888 5 dyld 0x104171ef4 start + 1868 Thread 0 crashed with ARM Thread State (64-bit): x0: 0x0000000000000006 x1: 0x0000000000000004 x2: 0x000000016bdd2810 x3: 0x0000000000000172 x4: 0x000000016bdd2410 x5: 0x0000000000000000 x6: 0x000000016bdd1400 x7: 0x000000016bdd1460 x8: 0x0000000000000020 x9: 0x000000016bdd237c x10: 0x000000000000000a x11: 0x0000000000000000 x12: 0x0000000000000038 x13: 0x0000000000000000 x14: 0x0000000188e77f9d x15: 0x0000000000008000 x16: 0x0000000000000209 x17: 0x000000010416f37c x18: 0x0000000000000000 x19: 0x0000000000000000 x20: 0x000000016bdd2410 x21: 0x0000000000000172 x22: 0x000000016bdd2810 x23: 0x0000000000000004 x24: 0x0000000000000006 x25: 0x00000000000000a8 x26: 0x000000016bdd32d8 x27: 0x000000010405e090 x28: 0x0000000000000001 fp: 0x000000016bdd23e0 lr: 0x00000001041e50cc sp: 0x000000016bdd23a0 pc: 0x00000001041da4c8 cpsr: 0x80001000 far: 0x0000000000000000 esr: 0x56000080 Address size fault Binary Images: 0x10416c000 - 0x1041f7fff dyld (*) &lt;4fe051cf-29dc-3f02-890b-33144fa09253&gt; /usr/lib/dyld 0x10402c000 - 0x10403ffff com.asix.dext.pciedevice (0.1.6) &lt;ece57abf-0633-3c3b-8427-fb25cc706343&gt; /Library/SystemExtensions/*/com.asix.dext.pciedevice 0x0 - 0xffffffffffffffff ??? (*) &lt;00000000-0000-0000-0000-000000000000&gt; ??? External Modification Summary: Calls made by other processes targeting this process: task_for_pid: 0 thread_create: 0 thread_set_state: 0 Calls made by this process: task_for_pid: 0 thread_create: 0 thread_set_state: 0 Calls made by all processes on this machine: task_for_pid: 0 thread_create: 0 thread_set_state: 0 VM Region Summary: ReadOnly portion of Libraries: Total=8612K resident=0K(0%) swapped_out_or_unallocated=8612K(100%) Writable regions: Total=12.2M written=0K(0%) resident=0K(0%) swapped_out=0K(0%) unallocated=12.2M(100%) Is it expected that this should work? Is this a known issue? Is there any workaround for it? Should I file feedback or a DTS?

I have a dext that creates a periodic timer on its own dispatch queue. The callback is declared as follows: virtual void HandleTimer( OSAction *action, uint64_t time ) TYPE(IOTimerDispatchSource::TimerOccurred); The timer is allocated as follows: CreateActionHandleTimer( size, &ivars->TimerHandler ); IODispatchQueue::Create( "TimerQueue", 0, 0, &ivars->TimerDispatchQueue ); IOTimerDispatchSource::Create( ivars->TimerDispatchQueue, &ivars->TimerDispatchSrc ); I can start up the timer and it works just fine. However, in my Stop() method, when trying to shut the timer down, I get an assertion in OSAction::Cancel() for TimerHandler: Assertion failed: (queue), function Cancel, file uioserver.cpp, line 4401. What does this assertion indicate or is the source code available? If so, where? I'm using macOS 15.5. Note I am attempting to cancel the handler after the dispatch source and queue are canceled and the cleanup methods have been called (which is working). But, cancelling TimerHandler first also asserts.

I need to implement an app that exchanges data with peripherals through TypeC on Apple 15 phones, but I have two questions that I need to ask for help: Which library is used to communicate with peripherals through the TypeC port of the Apple mobile phone? Do peripherals need to pass MFi authentication before they can communicate with the App?

I'm trying to implement a custom back button in a CPInformationTemplate using CPBarButton. It works as expected on iOS 18 — the button appears in the navigation bar and correctly pops the template when tapped. However, on iOS 16 devices, the custom back button does not respond to taps at all. The reason I need a custom back button is because I want to perform cleanup and reset logic before popping the template. Is there any workaround for making this work on iOS 16? Or is there a recommended way to hook into the system back button behavior so that I can execute code when the template is dismissed?