无法播放 Midi 文件

Question

我正在尝试创建和播放一系列 MIDI、音符。 但是我的播放器没有正确创建：

func playMusic(){
    
    
    // Adding notes

    var time = MusicTimeStamp(0.0)

    let contents:NSURL = Bundle.main.url(forResource: "data", withExtension: "midi")! as NSURL
    
    let sequencer = AppleSequencer()
    
    let track1 = sequencer.newTrack()
    for notee in TestOne().notes{
        
        var number = freqsScale[notee.frequency] ?? 0
        number += 11
        let d1 = Duration(seconds: Double(notee.distance))
        let d2 = Duration(seconds: Double(time))
        track1?.add( midiNoteData: MIDINoteData(noteNumber: UInt8(number), velocity: 64, channel: 0, duration: d1 , position: d2 ))
        time += Double(notee.distance)
        
    }
    sequencer.setLength(Duration(seconds: time))
    if contents.startAccessingSecurityScopedResource() {
        try! sequencer.genData()!.write(to: contents as URL)
    }
    contents.stopAccessingSecurityScopedResource()
    

    
    let soundbank = Bundle.main.url(forResource: "gs_instruments", withExtension: "dls")
   
    
    
    var mp = AVMIDIPlayer()
    do {
        mp = try AVMIDIPlayer(contentsOf: contents as URL, soundBankURL: soundbank)
    }
    catch{
        print("player not created")
    }
    
    mp.prepareToPlay()
    mp.play()
           
       
    var completion:AVMIDIPlayerCompletionHandler = {print("done")}
    mp.play(completion)

    
}

当我尝试运行此代码时，当我尝试创建 MIDI 播放器时出现以下错误：

[seq] SequenceTrack.cpp:1037 合并：无效节拍范围

[seqp] StandardMidiFile.cpp:152 ReadStandardMidiFile: 未知文件类型

可能是什么原因造成的，我该如何解决？