According to the Apple docs, you should be able to connect audio nodes to an AVAudioEngine instance during runtime, but I'm getting a crash while trying to do so, in particular, when trying to connect instances of AVAudioUnitTimePitch or AVAudioUnitVarispeed to an AVAudioEngine with manual rendering mode enabled. The error message I get is: Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'player started when in a disconnected state' In my code, first, I configure the audio engine: let engine = AVAudioEngine() let format = AVAudioFormat(standardFormatWithSampleRate: 48000, channels: 2)! try! engine.enableManualRenderingMode(.offline, format: format, maximumFrameCount: 1024) try! engine.start() Then, I try to attach the player to the engine: let player = AVAudioPlayerNode() configureEngine(player: player, useVarispeed: true) player.play() // this is the line that causes the crash Finally, this is the function I use to configure the engine nodes graph: func configureEngine(player: AVAudioPlayerNode, useVarispeed: Bool) { engine.attach(player) guard useVarispeed else { engine.connect(player, to: engine.mainMixerNode, format: format) return } let varispeed = AVAudioUnitVarispeed() engine.attach(varispeed) engine.connect(player, to: varispeed, format: format) engine.connect(varispeed, to: engine.mainMixerNode, format: format) } If I pass false as the value for the useVarispeed parameter, the crash goes away. What is even more interesting is that if I add a dummy player node before starting the engine, the crash goes away too 🤷‍♂️ Could anyone please add clarity on what's going on here? Is this a bug or a limitation of the framework that I'm not aware of? Here's a simple project demonstrating the problem: https://github.com/rlaguilar/AVAudioEngineBug

I'm trying to use the sample code associated to the talk Author fragmented MPEG-4 content with AVAssetWriter which can be found here. It works well when I run it on macOS, but after adapting it to run in iOS (basically moving the code in the main file to a view controller), it doesn't work. The problem is that the function: assetWriter(_:didOutputSegmentData:segmentType:segmentReport:) is never called for the last segment. In macOS, the last segment is reported after calling the function AVAssetWriter.finishWriting(completionHandler:), but before the completionHandler parameter block is invoked. In iOS, nothing happens at that point. Is there anything I could do from my side to fix this problem? Thanks in advance!