AVAudioEngine.connect crash on hardware not simulator

Question

var engine:AVAudioEngine!
var format = engine.inputNode.inputFormat(forBus: 0)
engine.connect(engine.inputNode, to: engine.mainMixerNode, format: format)


        

Answer 1

I figure it out. I just set the AVAudioSession category type wrong. If you have the same error take a look at AVAudioSession and make sure that your AVAudioSession category is in the right setting for microphone permission. for instance

AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord, with: .mixWithOthers)

with this setting will allow app to use microphone and play sound in the same time.