How to play a midi file with audiokit's MIDIPlayer?

Question

I am trying to play a MIDI file using audiokit's MIDIPlayer. I have the following code:

import SwiftUI
import AudioKit

struct ContentView: View {
    @StateObject var midi = MIDIWrapper()
    
    var body: some View {
        Button(action: {midi.play()}, label: {Text("play")})     
    }
}

class MIDIWrapper: ObservableObject {
    
    let engine = AudioEngine()
    var instrument = AppleSampler()
    let player: MIDIPlayer
    
    init() {
        engine.output = instrument
        
        try? engine.start()
        
        player = MIDIPlayer(audioEngine: engine.avEngine, filename: "cdec.mid")
    }
    
    func play() -> () {
        player.play()
    }  
}

When I run this on my iPhone 13 I get the following error:

           AVAEInternal.h:109   [AVAudioSequencer.mm:121:-[AVAudioSequencer(AVAudioSequencer_Player) startAndReturnError:]: (impl->Start()): error -10852
MIDIPlayer.swift:play():121:Could not start the sequencer (MIDIPlayer.swift:play():121)

Could anyone tell me how I can fix this?

Answer 1

The filename should be without extension. The extension is added in the initializer of MIDIPlayer. Thanks to Nick Culbertson from Moby Pixel for pointing this out.

For people looking to play MIDI files with Audiokit, I would also recommend looking at the AppleSequencer class. Code examples can be found in the Audiokit Cookbook.