I can compile this #import <Cocoa/Cocoa.h> @interface AppDelegate : NSObject <NSApplicationDelegate> @property (strong) NSWindow *window; @property (strong) NSSlider *slider; @end @implementation AppDelegate - (void)applicationDidFinishLaunching:(NSNotification *)notification { // Window size NSRect frame = NSMakeRect(0, 0, 400, 300); NSUInteger style = NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskResizable; self.window = [[NSWindow alloc] initWithContentRect:frame styleMask:style backing:NSBackingStoreBuffered defer:NO]; [self.window setTitle:@"Centered Slider Example"]; [self.window makeKeyAndOrderFront:nil]; // Slider size CGFloat sliderWidth = 200; CGFloat sliderHeight = 32; CGFloat windowWidth = self.window.frame.size.width; CGFloat windowHeight = self.window.frame.size.height; CGFloat sliderX = (windowWidth - sliderWidth) / 2; CGFloat sliderY = (windowHeight - sliderHeight) / 2; self.slider = [[NSSlider alloc] initWithFrame:NSMakeRect(sliderX, sliderY, sliderWidth, sliderHeight)]; [self.slider setMinValue:0]; [self.slider setMaxValue:100]; [self.slider setDoubleValue:50]; [self.window.contentView addSubview:self.slider]; } @end int main(int argc, const char * argv[]) { @autoreleasepool { NSApplication *app = [NSApplication sharedApplication]; AppDelegate *delegate = [[AppDelegate alloc] init]; [app setDelegate:delegate]; [app run]; } return 0; } with (base) johnzhou@Johns-MacBook-Pro liquidglasstest % clang -framework Foundation -framework AppKit testobjc.m and get this neat liquid glass effect: https://github.com/user-attachments/assets/4199493b-6011-4ad0-9c9f-25db8585e547 However if I use pyobjc to make an equivalent import sys from Cocoa import ( NSApplication, NSApp, NSWindow, NSSlider, NSMakeRect, NSWindowStyleMaskTitled, NSWindowStyleMaskClosable, NSWindowStyleMaskResizable, NSBackingStoreBuffered, NSObject ) class AppDelegate(NSObject): def applicationDidFinishLaunching_(self, notification): # Create the main window window_size = NSMakeRect(0, 0, 400, 300) style = NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskResizable self.window = NSWindow.alloc().initWithContentRect_styleMask_backing_defer_( window_size, style, NSBackingStoreBuffered, False ) self.window.setTitle_("Centered Slider Example") self.window.makeKeyAndOrderFront_(None) # Slider size and positioning slider_width = 200 slider_height = 32 window_width = self.window.frame().size.width window_height = self.window.frame().size.height slider_x = (window_width - slider_width) / 2 slider_y = (window_height - slider_height) / 2 self.slider = NSSlider.alloc().initWithFrame_(NSMakeRect(slider_x, slider_y, slider_width, slider_height)) self.slider.setMinValue_(0) self.slider.setMaxValue_(100) self.slider.setDoubleValue_(50) self.window.contentView().addSubview_(self.slider) if __name__ == "__main__": app = NSApplication.sharedApplication() delegate = AppDelegate.alloc().init() app.setDelegate_(delegate) app.run() I get a result shown at https://github.com/user-attachments/assets/7da022bc-122b-491d-9e08-030dcb9337c3 which does not have the new liquid glass effect. Why is this? Is this perhaps related to the requirement that you must compile on latest Xcode as indicated in the docs? Why, is the compiler doing some magic?

I have been banging my head against this problem for a bit now. I am trying to build a bidirectional, infinitely scrolling list that implements these core requirements: Loads data up/down on the fly as the user scrolls Preserves scroll velocity as the list is updated Restores the scroll to the exact visual location after data has changed Ensures no flicker when restoring scroll position - the user cannot know the list has updated and should continue scrolling as normal Because LazyVStack does not play well with animations, I am opting to go with VStack and am implementing my own sliding window for data. This means that data can be removed as well as added, and a simple application of a height delta is not enough when restoring position. So far I have tried many things: Relying on ScrollPosition - simply does not work by itself as described (swift UI trying to keep the position stable with ID's) Relying on ScrollPosition.scrollTo - only kind of works with ID, no way to restore position with pixel perfect accuracy Intercepting the UIKit scrollView instance, using it to record and access the top row's position, mutating data and then queuing a scroll restoration using CATransaction.setCompletionBlock - this is the closest I've come, and it satisfies the top 3 requirements but sometimes I get a flicker on slightly heavier lists What I would really like, is a way of using ScrollView and granularly hooking into the lifecycle of the view after layout, and just before draw. At this point I would update the relevant scroll positions, and allow draw to continue. Is this possible? My knowledge is very limited at this point, but I believe I may be able to achieve something of the sort by swizzling layerWillDraw? Does this make sense, and is it prudent? In general, I'm very interesting in hearing what people have to say about the above, as well as this problem in general.

After swapping the -objectAtIndex: method using method_exchangeImplementations, it will cause continuous memory growth. Connect the iPhone and run the provided project. Continuously tap the iPhone screen. Observe Memory; it will keep growing. Sample code

I’m an amateur developer working on a free utility for composers/producers, for which the macOS release needs to create and name RTP-MIDI sessions in Audio MIDI Setup from the command line (so I can ship a small C helper instead of telling users to click through the UI). Here’s what I’ve tried so far, without luck: • Plist hacks: Injecting entries into ~/Library/Audio/MIDI Configurations/*.mcfg works when AMS is closed, but AMS immediately locks and reverts my changes when it’s open. • CoreMIDI C API: I can create virtual ports with MIDISourceCreate, but attempting MIDIObjectGetDataProperty on the apple.midirtp.session plugin always returns err –10836. • Obj-C & Swift: Loading MIDINetworkSession and calling defaultSession, init, setNetworkName: and setting enabled = YES doesn’t produce a new session object in the Network panel. • dlopen/dlsym: I extracted the real CoreMIDI binary out of the dyld shared cache and tried binding _MIDINetworkSessionCreate, _SetName, _SetEnabled, etc., but all the symbols come back null or my tool segfaults. • Plugin registration: I’ve pulled the factory UUID (70C9C5EA-7C65-11D8-B317-000393A34B5A) from /System/Library/Extensions/AppleMIDIRTPDriver.plugin/Contents/Info.plist and called CFPlugInRegisterFactories, but it still never exposes the session-creation calls. At this point I’m convinced I’m either loading the wrong binary or missing one critical step in registering the RTP-MIDI plugin’s private API. Can anyone point me to: The exact path of the dylib or bundle that actually exports the MIDINetworkSessionCreate/MIDINetworkSessionSetName/MIDINetworkSessionSetEnabled symbols? A minimal working snippet (C or Obj-C) that reliably creates and names a Network-MIDI session? Any pointers, sample code, or even ideas about where Apple hides this functionality on macOS 15 would be hugely appreciated. Thanks!

Under multiple display screens (left and right screens), when a commonly used app application clicks "Window" -> "Move to..." When it comes to this, the app cannot be completely moved to the other window but instead moves to the middle of the two Windows for display. Is this a bug of the system?

Hi All my app randomly crash on very rare case. when bring app into foreground I checked the code: { NSError *error = nil; if (![sender authenticateWithPassword:MyManager.sharedManager.service.authToken.accessToken error:&amp;error]) { ... ... ... } } accessToken is NSString type, was that because accessToken is deallocated? Manager and service could not be nil at all. Last Exception Backtrace: 0 CoreFoundation 0x18b04d2ec __exceptionPreprocess + 164 1 libobjc.A.dylib 0x1884d1a7c objc_exception_throw + 88 2 CoreFoundation 0x18b0b767c +[NSObject(NSObject) _copyDescription] + 0 3 CoreFoundation 0x18af64b84 ___forwarding___ + 1492 4 CoreFoundation 0x18af644f0 _CF_forwarding_prep_0 + 96 5 PTComms 0x102adafac __45-[XMPPStream authenticateWithPassword:error:]_block_invoke + 1884 6 libdispatch.dylib 0x192ecb584 _dispatch_client_callout + 16 7 libdispatch.dylib 0x192ec1b4c _dispatch_sync_invoke_and_complete_recurse + 64 8 libdispatch.dylib 0x192ec15dc _dispatch_sync_f_slow + 176 9 PTComms 0x102ada760 -[XMPPStream authenticateWithPassword:error:] + 516 10 PTComms 0x102a7b6f0 -[CommsService xmppStreamDidConnect:] + 160 11 CoreFoundation 0x18af64434 __invoking___ + 148 12 CoreFoundation 0x18af65044 -[NSInvocation invoke] + 424 13 CoreFoundation 0x18afbb6b8 -[NSInvocation invokeWithTarget:] + 64 14 PTComms 0x102b391c8 __42-[GCDMulticastDelegate forwardInvocation:]_block_invoke + 68 15 libdispatch.dylib 0x192eb1aac _dispatch_call_block_and_release + 32 16 libdispatch.dylib 0x192ecb584 _dispatch_client_callout + 16 17 libdispatch.dylib 0x192ee8574 _dispatch_main_queue_drain.cold.5 + 812 18 libdispatch.dylib 0x192ec0d30 _dispatch_main_queue_drain + 180 19 libdispatch.dylib 0x192ec0c6c _dispatch_main_queue_callback_4CF + 44 20 CoreFoundation 0x18afa62b4 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 16 21 CoreFoundation 0x18afa40b0 __CFRunLoopRun + 1980 22 CoreFoundation 0x18afc8700 CFRunLoopRunSpecific + 572 23 GraphicsServices 0x1d7b09190 GSEventRunModal + 168 24 UIKitCore 0x18dbe6240 -[UIApplication _run] + 816 25 UIKitCore 0x18dbe4470 UIApplicationMain + 336 26 VoceraEdgeComms 0x102542318 0x10253c000 + 25368 27 dyld 0x1b19cbad8 start + 5964 Thread 0 name: Dispatch queue: xmpp Thread 0 Crashed: 0 libsystem_kernel.dylib 0x1dbb3a1dc __pthread_kill + 8 1 libsystem_pthread.dylib 0x2154b8b40 pthread_kill + 268 2 libsystem_c.dylib 0x192f6d360 __abort + 132 3 libsystem_c.dylib 0x192f6d2dc abort + 136 4 libc++abi.dylib 0x2153e25a0 abort_message + 132 5 libc++abi.dylib 0x2153d0f10 demangling_terminate_handler() + 344 6 libobjc.A.dylib 0x1884d3bb8 _objc_terminate() + 156 7 PTCore 0x1061f0d98 FIRCLSTerminateHandler() (.cold.3) + 56 8 PTCore 0x1060ef7e8 FIRCLSTerminateHandler() + 276 9 libc++abi.dylib 0x2153e18b4 std::__terminate(void (*)()) + 16 10 libc++abi.dylib 0x2153e4e1c __cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception*) + 88 11 libc++abi.dylib 0x2153e4dc4 __cxa_throw + 92 12 libobjc.A.dylib 0x1884d1be4 objc_exception_throw + 448 13 CoreFoundation 0x18b0b767c -[NSObject(NSObject) doesNotRecognizeSelector:] + 364 14 CoreFoundation 0x18af64b84 ___forwarding___ + 1492 15 CoreFoundation 0x18af644f0 _CF_forwarding_prep_0 + 96 16 PTComms 0x102adafac __45-[XMPPStream authenticateWithPassword:error:]_block_invoke + Thanks, CrashReporter.txt

Is there a way to prevent or handle our application's crash if a third-party library makes a bad memory access? Basically, I want to know if using a buggy library (that causes bad memory access) will automatically make our application inherit those crashes, leading to our app crashing as well. If there is a way to prevent the crash, what methods can be used to do so? Thread 13: EXC_BAD_ACCESS (code=1, address=0x3a7d300)

When I run app, it works on iOS16+ device. But when I run on iOS15 device just working on debug mode, if I run release or profile modeI got runtime error: Log: (lldb) dyld[4928]: Symbol not found: (_objc_claimAutoreleasedReturnValue) Referenced from: '/private/var/containers/Bundle/Application/C724D7C6-82FA-4AF3-AE83-EC035B4429A5/Runner.app/Frameworks/geolocator_apple.framework/geolocator_apple' Expected in: '/usr/lib/libobjc.A.dylib' thread #1, stop reason = signal SIGABRT frame #0: 0x0000000106cbb2cc dyld`__abort_with_payload + 8 dyld`__abort_with_payload: -&amp;gt; 0x106cbb2cc &amp;lt;+8&amp;gt;: b.lo 0x106cbb2e8 ; &amp;lt;+36&amp;gt; 0x106cbb2d0 &amp;lt;+12&amp;gt;: stp x29, x30, [sp, #-0x10]! 0x106cbb2d4 &amp;lt;+16&amp;gt;: mov x29, sp 0x106cbb2d8 &amp;lt;+20&amp;gt;: bl 0x106c8164c ; cerror_nocancel Target 0: (Runner) stopped. Flutter doctor : Doctor summary (to see all details, run flutter doctor -v): [✓] Flutter (Channel stable, 3.29.2, on macOS 15.2 24C101 darwin-arm64, locale en-VN) [✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0) [✓] Xcode - develop for iOS and macOS (Xcode 16.2) [✓] Chrome - develop for the web [✓] Android Studio (version 2024.2) [✓] VS Code (version 1.97.2)

My company wants to be insure that if my Objective-C to Swift conversions fail in anyway, that the app can revert to using the older Objective-C code. By using a remotely controllable flag, the app can switch which code runs as, both are compiled into the app. Essentially, I create a protocol that describes the original class, then both classes (with a "s" or "o" appended to them) conform to the protocol. Protocol: Object Objective-C class: oObject Swift class: sObject That said, I hit one issue that I just can't seem reason out. I create a Objective-C function that returns the appropriate class: Class<Object> classObject(void) { if (myFlag) { return [sObject class]; } else { return [oObject class]; } } Swift deals with this really well - I can create an initialized object using: let object = classObject().init() but I cannot find a way to do this in Objective-C: Object *object = [[classSalesForceData() alloc] init]; fails with "No known class method for selector 'alloc'" Is there a way to do this? David PS: my workaround is to return an allocated object: Object *createObject(void) { if (myFlag) { return [sObject alloc]; } else { return [oObject alloc]; } }

After the app is put in background for sometime and brought in to foreground and the app crashes each time with a different thread stack entries but all of them states same exception reason.

Hello! I have a swift program that tracks the location of a ball (through the back camera). It seems to be working fine, but the only issue is the run time, particularly my concatenate, normalize, and argmax functions, which are meant to be a 1 to 1 copy of the PyTorch argmax function and the following python lines: imgs = np.concatenate((img, img_prev, img_preprev), axis=2) imgs = imgs.astype(np.float32)/255.0 imgs = np.rollaxis(imgs, 2, 0) inp = np.expand_dims(imgs, axis=0) # used to pass into model However, I need my program to run in real time and in an ideal world, I want it to run way under real time. Below is a run down of the run times that result from my code: Starting model inference Setup took: 0.0 seconds Resize took: 0.03741896152496338 seconds Concatenation took: 0.3359949588775635 seconds Normalization took: 0.9906361103057861 seconds Model prediction took: 0.3425499200820923 seconds Argmax took: 28.17007803916931 seconds Postprocess took: 0.054128050804138184 seconds Model inference took 29.934185028076172 seconds Here are the concatenateBuffers, normalizeBuffers, and argmax functions that I use: func concatenateBuffers(_ buffers: [CVPixelBuffer?]) -> CVPixelBuffer? { guard buffers.count == 3, let first = buffers[0] else { return nil } let width = CVPixelBufferGetWidth(first) let height = CVPixelBufferGetHeight(first) let targetChannels = 9 var concatenated: CVPixelBuffer? let attrs = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue] as CFDictionary CVPixelBufferCreate(kCFAllocatorDefault, width, height, kCVPixelFormatType_32BGRA, attrs, &concatenated) guard let output = concatenated else { return nil } CVPixelBufferLockBaseAddress(output, []) defer { CVPixelBufferUnlockBaseAddress(output, []) } guard let outputData = CVPixelBufferGetBaseAddress(output) else { return nil } let outputPtr = UnsafeMutablePointer<UInt8>(OpaquePointer(outputData)) // Lock all input buffers at once buffers.forEach { buffer in guard let buffer = buffer else { return } CVPixelBufferLockBaseAddress(buffer, .readOnly) } defer { buffers.forEach { CVPixelBufferUnlockBaseAddress($0!, .readOnly) } } // Process each input buffer for (frameIdx, buffer) in buffers.enumerated() { guard let buffer = buffer, let inputData = CVPixelBufferGetBaseAddress(buffer) else { continue } let inputPtr = UnsafePointer<UInt8>(OpaquePointer(inputData)) let bytesPerRow = CVPixelBufferGetBytesPerRow(buffer) let totalPixels = width * height // Process all pixels in one go for this frame for i in 0..<totalPixels { let y = i / width let x = i % width let inputOffset = y * bytesPerRow + x * 4 let outputOffset = i * targetChannels + frameIdx * 3 // BGR order to match numpy outputPtr[outputOffset] = inputPtr[inputOffset + 2] // B outputPtr[outputOffset + 1] = inputPtr[inputOffset + 1] // G outputPtr[outputOffset + 2] = inputPtr[inputOffset] // R } } return output } func normalizeBuffer(_ buffer: CVPixelBuffer?) -> MLMultiArray? { guard let input = buffer else { return nil } let width = CVPixelBufferGetWidth(input) let height = CVPixelBufferGetHeight(input) let channels = 9 CVPixelBufferLockBaseAddress(input, .readOnly) defer { CVPixelBufferUnlockBaseAddress(input, .readOnly) } guard let inputData = CVPixelBufferGetBaseAddress(input) else { return nil } let shape = [1, NSNumber(value: channels), NSNumber(value: height), NSNumber(value: width)] guard let output = try? MLMultiArray(shape: shape, dataType: .float32) else { return nil } let inputPtr = inputData.assumingMemoryBound(to: UInt8.self) let bytesPerRow = CVPixelBufferGetBytesPerRow(input) let ptr = UnsafeMutablePointer<Float>(OpaquePointer(output.dataPointer)) let totalSize = width * height for c in 0..<channels { for idx in 0..<totalSize { let h = idx / width let w = idx % width let inputIdx = h * bytesPerRow + w * channels + c ptr[c * totalSize + idx] = Float(inputPtr[inputIdx]) / 255.0 } } return output } func argmax(_ array: MLMultiArray) -> MLMultiArray? { let shape = array.shape.map { $0.intValue } guard shape.count == 3, shape[0] == 1, shape[1] == 256, shape[2] == 230400 else { return nil } guard let output = try? MLMultiArray(shape: [1, NSNumber(value: 230400)], dataType: .int32) else { return nil } let ptr = UnsafePointer<Float>(OpaquePointer(array.dataPointer)) let outputPtr = UnsafeMutablePointer<Int32>(OpaquePointer(output.dataPointer)) let channelSize = 230400 for pos in 0..<230400 { var maxValue = -Float.infinity var maxIndex: Int32 = 0 for channel in 0..<256 { let value = ptr[channel * channelSize + pos] if value > maxValue { maxValue = value maxIndex = Int32(channel) } } outputPtr[pos] = maxIndex } return output } Are there any glaring areas of inefficiencies that can be reduced to allow for under real time processing whilst following the same logic as found in the python code exactly? Would using Obj-C speed things up for some reason? Are there any tools I can use so I don't have to write these functions myself? Additionally, in the classes init, function, I tried to check the compute units being used since I feel 0.34 seconds for a singular model prediction is also far too long, but no print statements are showing for some reason: init() { guard let loadedModel = try? BallTrackerModel() else { fatalError("Could not load model") } let config = MLModelConfiguration() config.computeUnits = .all guard let configuredModel = try? BallTrackerModel(configuration: config) else { fatalError("Could not configure model") } self.model = configuredModel print("model loaded with compute units \(config.computeUnits.rawValue)") } Thanks!

Hello everyone, There is one thing about Objective-C's memory management that confuses me, which is a returned object's lifetime from methods with names doesn't start with "alloc", "new", "copy", or "mutableCopy". Take this as an example, when using NSBitmapImageRep's representationUsingType:properties: method, it returns an NSData object (reference: https://developer.apple.com/documentation/appkit/nsbitmapimagerep/representation(using:properties:)?language=objc). While testing this out, the NSData seemed to be an owned object (it doesn't get released until the end of the program). From what I understand, this may be an auto-released object which is released at the end of an autorelease pool block. Could someone explain this in more detail? What if I want to release that NSData object before the end of the autorelease pool block? How can I know which object is autoreleased, borrowed, or owned?

I have a class object created dynamically using Runtime, and I want to release some manually allocated memory resources when this object is deallocated. To achieve this, I added a custom implementation of the dealloc method using the following code: SEL aSel = NSSelectorFromString(@"dealloc"); class_addMethod(kvoClass, aSel, (IMP)custom_dealloc, method_getTypeEncoding(class_getInstanceMethod(kvoClass, aSel))); However, I encountered some issues. If I don't call the superclass's dealloc method in the cus_dealloc function, the superclass's dealloc implementation will not be executed. On the other hand, if I explicitly call the superclass's dealloc method, the program crashes. Here is the implementation of the cus_dealloc function: void custom_dealloc(id self, SEL _cmd) { // Release other memory ![]("https://developer.apple.com/forums/content/attachment/c7b0c16b-be23-4776-b8db-f22b661c5e7d" "title=iShot_2025-01-03_19.31.34.png;width=1080;height=1895") Class superClass = class_getSuperclass(object_getClass(self)); void (*originIMP)(struct objc_super *, SEL, ...) = (void *)objc_msgSendSuper; struct objc_super *objcSuper = &(struct objc_super){self, superClass}; originIMP(objcSuper, _cmd); } demo

My app's top crash is a mysterious one and I can't seem to figure it out. It always crashes on _objc_fatalv(unsigned long long, unsigned long long, char const*, char*) But the stack traces include a few different possible culprits like NavigationBridge_PhoneTV.pushTarget(isDetail:) UIKitNavigationBridge.update(environment:) ViewRendererHost.updateGraph() UIScrollView(SwiftUI) _swiftui_adjustsContentInsetWhenScrollDisabled Crash reports here: 2024-12-02_21-37-21.7864_-0600-1e78918e5586309b96a1c2986ff722778dec8a77.crash 2024-12-02_19-18-29.1251_-0500-a2fc5513683cd647b4adbbe03cc59e4a09237b5f.crash 2024-12-01_11-59-09.8888_-0500-9eb224ab3d37e76d0b966ea83473f584ac3bbe18.crash 2024-11-28_17-17-38.4808_+0100-46208989f016fbefd16c30873a88c2ef61dd91a1.crash Hopefully someone here can shed some light. For context we use a lot of UIHostingController's to bridge our SwiftUI views.

Hey there! My app's top crash is a mysterious one and I can't seem to figure it out. Hopefully someone here can shed some light. For context we use a lot of UIHostingController's to bridge our SwiftUI views. Crashed: com.apple.main-thread 0 libsystem_kernel.dylib 0x13ec4 __abort_with_payload + 8 1 libsystem_kernel.dylib 0x33bec abort_with_payload_wrapper_internal + 104 2 libsystem_kernel.dylib 0x33b84 abort_with_payload_wrapper_internal + 30 3 libobjc.A.dylib 0xbea0 _objc_fatalv(unsigned long long, unsigned long long, char const*, char*) + 116 4 libobjc.A.dylib 0xbe2c _objc_fatalv(unsigned long long, unsigned long long, char const*, char*) + 30 5 libobjc.A.dylib 0xb040 weak_register_no_lock + 396 6 libobjc.A.dylib 0xa9bc objc_initWeak + 440 7 libswiftCore.dylib 0x43abe8 swift_unknownObjectWeakInit + 92 8 SwiftUI 0xf40cc NavigationBridge_PhoneTV.pushTarget(isDetail:) + 376 9 SwiftUI 0xf9490 UIKitNavigationBridge.update(environment:) + 1060 10 SwiftUI 0x5b51c UIHostingController._update(environment:) + 156 11 SwiftUI 0x96a30 _UIHostingView.updateEnvironment() + 3484 12 SwiftUICore 0xa0d0a0 closure #1 in ViewRendererHost.updateGraph() + 364 13 SwiftUICore 0xa0ca08 ViewRendererHost.updateGraph() + 180 14 SwiftUICore 0xa0d7d4 closure #1 in ViewRendererHost.render(interval:updateDisplayList:targetTimestamp:) + 368 15 SwiftUICore 0xa0b0d4 ViewRendererHost.render(interval:updateDisplayList:targetTimestamp:) + 556 16 SwiftUI 0x8f1634 UIHostingViewBase.renderForPreferences(updateDisplayList:) + 168 17 SwiftUI 0x8f495c closure #1 in UIHostingViewBase.requestImmediateUpdate() + 72 18 SwiftUI 0xcc700 thunk for @escaping @callee_guaranteed () -> () + 36 19 libdispatch.dylib 0x2370 _dispatch_call_block_and_release + 32 20 libdispatch.dylib 0x40d0 _dispatch_client_callout + 20 21 libdispatch.dylib 0x129e0 _dispatch_main_queue_drain + 980 22 libdispatch.dylib 0x125fc _dispatch_main_queue_callback_4CF + 44 23 CoreFoundation 0x56204 CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE + 16 24 CoreFoundation 0x53440 __CFRunLoopRun + 1996 25 CoreFoundation 0x52830 CFRunLoopRunSpecific + 588 26 GraphicsServices 0x11c4 GSEventRunModal + 164 27 UIKitCore 0x3d2eb0 -[UIApplication _run] + 816 28 UIKitCore 0x4815b4 UIApplicationMain + 340 29 (MyApp) 0x1a7e0 main + 8 (main.swift:8) 30 ??? 0x1bf97eec8 (Missing)

This is similar to this post https://developer.apple.com/forums/thread/700770 on using objc_copyClassList to obtain the available classes. When iterating the list, I try casting the result to an instance of a protocol and that works fine: protocol DynamicCounter { init(controlledByPlayer: Bool, game: Game) } class BaseCounter: NSObject, DynamicCounter { } static func withAllClasses<R>( _ body: (UnsafeBufferPointer<AnyClass>) throws -> R ) rethrows -> R { var count: UInt32 = 0 let classListPtr = objc_copyClassList(&count) defer { free(UnsafeMutableRawPointer(classListPtr)) } let classListBuffer = UnsafeBufferPointer( start: classListPtr, count: Int(count) ) return try body(classListBuffer) } static func initialize() { let monoClasses = withAllClasses { $0.compactMap { $0 as? DynamicCounter.Type } } for cl in monoClasses { cl.initialize() } } The above code works fine if I use DynamicCounter.Type on the cast but crashes if try casting to BaseCounter.Type instead. Is there a way to avoid the weird and non Swift classes?

I'll describe my crash with an example, looking for some insights into the reason why this is happening. @objc public protocol LauncherContainer { var launcher: Launcher { get } } @objc public protocol Launcher: UIViewControllerTransitioningDelegate { func initiateLaunch(url: URL, launchingHotInstance: Bool) } @objc final class LauncherContainer: NSObject, LauncherContainer, TabsContentCellTapHandler { ... init( ... ) { ... super.init() } ... // // ContentCellTapHandler // public func tabContentCellItemDidTap( tabId: String ) { ... launcher.initiateNewTabNavigation( tabId: tabId // Crash happens here ) } public class Launcher: NSObject, Launcher, FooterPillTapHandler { public func initiateNewTabNavigation(tabId: String) { ... } } public protocol TabsContentCellTapHandler: NSObject { func tabContentCellItemDidTap( tabId: String, }