Brief

An AUAudioUnit-based metronome demostration app

Implemented Features

• Beat counter in audio callback
• Use an AVAudioUnitSampler as click sound synthesizer
• Adujstable BPM
• Adjustable time signature X/Y for X and Y in [1, 32]

How to Use

• Copy AudioUnitMetronome.m, AudioUnitMetronome.h and MetronomeBeatChangedPerceivable.h to your project
• Register AudioUnitMetronome as below

   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
       [AUAudioUnit registerSubclass:[MetronomeAudioUnit class]
              asComponentDescription:desc
                                name:@"metr"
                             version:0];
   });

Note: make sure AudioUnitMetronome has been registered before you creating it.

• Create an AudioUnitMetronome via

[AVAudioUnit instantiateWithComponentDescription:desc
                                            options:kAudioComponentInstantiation_LoadOutOfProcess
                                  completionHandler:^(__kindof AVAudioUnit * _Nullable audioUnit, NSError * _Nullable error) {
//connect your audio nodes here
}];

• Set an id<MetronomeBeatChangedPerceivable> as delegate for AudioUnitMetronome if you want to get notification while beat changed, e.g. play click sound or display beat number.

For more informations, may refer to ViewController.m for more details.