I wrote the code below to pass my custom object Engine in MTAudioProcessingTapCallbacks Here is code: func getTap() -> MTAudioProcessingTap? {     var tap: Unmanaged<MTAudioProcessingTap>?           func onInit(tap:MTAudioProcessingTap,clientInfo:UnsafeMutableRawPointer?,tagStroageOut:UnsafeMutablePointer<UnsafeMutableRawPointer?>) {               let engine = Engine()       tagStroageOut.pointee = Unmanaged<Engine>.passUnretained(engine).toOpaque()     }                 var callback = MTAudioProcessingTapCallbacks(version: kMTAudioProcessingTapCallbacksVersion_0, clientInfo:nil, init: onInit, finalize: nil, prepare: nil, unprepare: nil) { tap, numberFrames, flags, bufferListInOut, numberFramesOut, flagsOut in               guard MTAudioProcessingTapGetSourceAudio(tap, numberFrames, bufferListInOut, flagsOut, nil, numberFramesOut) == noErr else {         preconditionFailure()       }               let storage = MTAudioProcessingTapGetStorage(tap)       let engine = Unmanaged<Engine>.fromOpaque(storage).takeUnretainedValue()               // This line crashed :       // ClientProcessingTapManager (14): EXC_BAD_ACCESS (code=1, address=0x544453e46ea0)       engine.dealWith(bufferPtr: bufferListInOut)     }     guard MTAudioProcessingTapCreate(kCFAllocatorDefault, &callback, kMTAudioProcessingTapCreationFlag_PostEffects, &tap) == noErr else{       fatalError()     }     return tap?.takeRetainedValue()   } } How can I do it?

I have an AVAudioEngine,but I don't know how to export the audio in AVAudioEngine to a file. Anyone can help?

I want to get animation interpolation during animation running. just like code below: Animator(begin:100,end:200).addListener({value in //here will be called when animation updates. print(value) }) But I can't find any API like the code above in iOS SDK.And I don't want to use any UIView or CALayer to get presentationLayer to get this value. So How can I do that?🤔🤔🤔

The new captureTextFromCamera API allow device to use OCR in UIResponder,but how can I know this device support OCR or not ? eg: iPhoneX:NO, iPhone13:YES

What I want is to make video 's rotation be from 0 to 90 degree in 0 ~ 2s. Here is the code: let layerIns = AVMutableVideoCompositionLayerInstruction(assetTrack: track) let endTransform = CGAffineTransform(rotationAngle: CGFloat(Double.pi / 2)) let timeRange = CMTimeRange(start: .zero, duration: CMTime(seconds: 2, preferredTimescale: 600)) layerIns.setTransformRamp(fromStart: .identity, toEnd: endTransform, timeRange: timeRange) But the center of rotation is top-left corner.. Which makes rotation effect look strange. I wonder how to change the video layer's anchor point to center point instead of top-left corner... related question on StackOverFlow :Question Link - https://stackoverflow.com/questions/65575655/how-to-change-the-settransformramp-s-transform-anchor-point