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

I have an AVMutableAudioMix and use MTAudioProcessingTap to process the audio data.But After I pass the buffer to AVAudioEngine and to render it with renderOffline,the audio has no any effects...How can I do it? Any idea? Here is the code for MTAudioProcessingTapProcessCallback var callback = MTAudioProcessingTapCallbacks(version: kMTAudioProcessingTapCallbacksVersion_0, clientInfo:UnsafeMutableRawPointer(Unmanaged.passUnretained(self.engine).toOpaque()), init: tapInit, finalize: tapFinalize, prepare: tapPrepare, unprepare: tapUnprepare) { 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()       // render the audio with effect       engine.render(bufferPtr: bufferListInOut,numberOfFrames: numberFrames)     } And here is the Engine code class Engine {   let engine = AVAudioEngine()       let player = AVAudioPlayerNode()   let pitchEffect = AVAudioUnitTimePitch()   let reverbEffect = AVAudioUnitReverb()   let rateEffect = AVAudioUnitVarispeed()   let volumeEffect = AVAudioUnitEQ()   let format = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 2, interleaved: false)!   init() {     engine.attach(player)     engine.attach(pitchEffect)     engine.attach(reverbEffect)     engine.attach(rateEffect)     engine.attach(volumeEffect)           engine.connect(player, to: pitchEffect, format: format)     engine.connect(pitchEffect, to: reverbEffect, format: format)     engine.connect(reverbEffect, to: rateEffect, format: format)     engine.connect(rateEffect, to: volumeEffect, format: format)     engine.connect(volumeEffect, to: engine.mainMixerNode, format: format)           try! engine.enableManualRenderingMode(.offline, format: format, maximumFrameCount: 4096)           reverbEffect.loadFactoryPreset(AVAudioUnitReverbPreset.largeRoom2)     reverbEffect.wetDryMix = 100     pitchEffect.pitch = 2100           try! engine.start()     player.play()   }       func render(bufferPtr:UnsafeMutablePointer<AudioBufferList>,numberOfFrames:CMItemCount) {     let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 4096)!     buffer.frameLength = AVAudioFrameCount(numberOfFrames)     buffer.mutableAudioBufferList.pointee = bufferPtr.pointee     self.player.scheduleBuffer(buffer) {       try! self.engine.renderOffline(AVAudioFrameCount(numberOfFrames), to: buffer)     }   } }

The GarageBand app can import both midi and recorded audio file into a single player to play. Just like this: My App have the same feature but I don't know how to implement it. I have tried the AVAudioSequencer,but it only can load and play MIDI file. I have tried the AVPlayer and AVPlayerItem,but it seems that it can't load the MIDI file. So How to combine MIDI file and audio file into a single AVPlayerItem or anything else to play?

This is the crash log from Firebase. Fatal Exception: NSInvalidArgumentException *** -[AVAssetWriter addInput:] Format ID 'lpcm' is not compatible with file type com.apple.m4a-audio But I can't reproduce the crash ... This is the demo code Does anyone know where the problem is ? let normalOutputSettings:[String:Any] = [     AVFormatIDKey : kAudioFormatLinearPCM,     AVSampleRateKey : 44100,     AVNumberOfChannelsKey : 2,     AVLinearPCMBitDepthKey : 16,     AVLinearPCMIsNonInterleaved : false,     AVLinearPCMIsFloatKey : false,     AVLinearPCMIsBigEndianKey : false   ] let writerInput = AVAssetWriterInput(mediaType: .audio, outputSettings: outputSettings) let outputURL = URL(fileURLWithPath: NSTemporaryDirectory() + UUID().uuidString + ".m4a") self.writer = try! AVAssetWriter(outputURL: outputURL, fileType: fileType) writer?.add(writerInput)

On iOS 18 we can see there is a colorful wave around screen when using siri, I want to implement one in my app. But I tried many ways but not succeed. Any idea?

I'm using AVFoundation to make a multi-track editor app, which can insert multiple track and clip, including scale some clip to change the speed of the clip, (also I'm not sure whether AVFoundation the best choice for me) but after making the scale with scaleTimeRange API, there is some short noise sound in play back. Also, sometimes it's fine when play AVMutableCompostion using AVPlayer with AVPlayerItem, but after exporting with AVAssetReader, will catch some short noise sounds in result file.... Not sure why. Here is the example project, which can build and run directly. https://github.com/luckysmg/daily_images/raw/refs/heads/main/TestDemo.zip

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

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?

AVAudioUnitTimePitch.latency is 0.09s on my debug devices. It will have a little time delay during render audio using `AVAudioEngine. I just want to change the pitch during playing audio. So how can I avoid this this latency??

Here is old doc https://developer.apple.com/library/archive/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Displays/Displays.html#//apple_ref/doc/uid/TP40013599-CH108-SW1 Where is new for it ?

The top padding of UINavigationBar 's value is UIApplication.shared.statusBarFrame.height or UIApplication.shared.keyWindow?.safeAreaInsets.top ? Here is image See the blue box of the image https://github.com/luckysmg/daily_images/blob/main/20220928153515.jpg?raw=true Because two value is the same on devices older than iPhone14 Pro but is not the same on iPhone14 Pro and iPhone 14 Pro max. Which is the right value to get?

The keyboard animation is private. How can we get the interpolation of the keyboard animation using a API?

When set metalLayer.presentsWithTransaction = true, and we call drawable.present() in bg thread (our rendering thread is not main thread), the app sometimes will crash with: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Modifications to the layout engine must not be performed from a background thread after it has been accessed from the main thread.' Any solution?

As title desc. Before iOS 16.6 is smooth. But iOS 16.6 is lagging. Seems iOS 17 beta4 is ok.. Maybe Apple should post a hotfix for iOS 16.6

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?🤔🤔🤔