ios - 合并中的音频不起作用

Question

我用这个作为引用:Concatenate two audio files in Swift and play them

我正在尝试创建一个闹钟，由于苹果政策的限制，你无法在过去 10 分钟的背景中执行代码，如果我选择退出背景模式并将我的应用程序留在前台，则“声音”会暂停，如果用户单击主页按钮，我需要声音继续播放，直到用户执行某些操作。由于静音/请勿打扰按钮，UILocalNotifs 不起作用。所以我想运行空白音频直到闹钟时间，然后播放声音。

所以我使用以下命令来运行它:

这是单击保存按钮时发生的情况(用户选择了闹钟时间)

 let seconds = Double(comp.second)
    let notification = UILocalNotification()
    notification.alertBody = "testBody"
    notification.fireDate = dueDatePicker.date
    notification.alertTitle = "testTitle"
    println("seconds:\(seconds)")



    var results:NSArray = managedObjectContext!.executeFetchRequest(request, error: &error)!

     let audioURL1 = NSBundle.mainBundle().URLForResource("alarm", withExtension: "m4a")!
    let audioURL2 = NSBundle.mainBundle().URLForResource("music", withExtension: "mp3")!
    println(audioURL1)
    println(audioURL2)
    println(task.uuid)

           mergeAudio2(audioURL1, audioURL2: audioURL2, time: seconds, uuid: task.uuid)

这是合并音频部分:

func mergeAudio2(audioURL: NSURL, audioURL2: NSURL, time:Double, uuid:String) {
    var error:NSError?

    var ok1 = false
    var ok2 = false


    //var documentsDirectory:String = paths[0] as! String

    //Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
    var composition = AVMutableComposition()
    var compositionAudioTrack1:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
    var compositionAudioTrack2:AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())

    //create new file to receive data
    var documentDirectoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first! as! NSURL
    var fileDestinationUrl = documentDirectoryURL.URLByAppendingPathComponent("resultmerge.wav")
    println(fileDestinationUrl)

    var file = "resultmerge.m4a"
    var dirs : [String] = (NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true) as? [String])!
    var dir = dirs[0] //documents directory
    var path = dir.stringByAppendingPathComponent(file)
    var pathURLarray:Array = (NSURL(fileURLWithPath: path)!).pathComponents!
    var pathURL:String = ""
    var final = ""
    var debut = ""

    for i in 1...(pathURLarray.count-1) {
        if i == pathURLarray.count-1 {
            final = ""
        } else {
            final = "/"
        }
        if i == 1 {
            debut = "/"
        } else {
            debut = ""
        }
        pathURL = debut + pathURL + (pathURLarray[i] as! String) + final
    }

    var checkValidation = NSFileManager.defaultManager()
    if checkValidation.fileExistsAtPath(pathURL) {
        println("file exist")
        if NSFileManager.defaultManager().removeItemAtURL(fileDestinationUrl, error: nil) {
            println("delete")
        }
    } else {
        println("no file")
    }

    var url1 = audioURL
    var url2 = audioURL2


    var avAsset1 = AVURLAsset(URL: url1, options: nil)
    var avAsset2 = AVURLAsset(URL: url2, options: nil)

    var tracks1 =  avAsset1.tracksWithMediaType(AVMediaTypeAudio)
    var tracks2 =  avAsset2.tracksWithMediaType(AVMediaTypeAudio)

    var assetTrack1:AVAssetTrack = tracks1[0] as! AVAssetTrack
    var assetTrack2:AVAssetTrack = tracks2[0] as! AVAssetTrack


    var duration1: CMTime = assetTrack1.timeRange.duration
    var duration2: CMTime = assetTrack2.timeRange.duration

    var timeRange1 = CMTimeRangeMake(kCMTimeZero, duration1)
    var timeRange2 = CMTimeRangeMake(duration1, duration2)


    ok1 = compositionAudioTrack1.insertTimeRange(timeRange1, ofTrack: assetTrack1, atTime: kCMTimeZero, error: nil)
    if ok1 {

        ok2 = compositionAudioTrack2.insertTimeRange(timeRange2, ofTrack: assetTrack2, atTime: duration1, error: nil)

        if ok2 {
            println("success")
        }
    }

    //AVAssetExportPresetPassthrough => concatenation


    var assetExport = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetAppleM4A)
    assetExport.outputFileType = AVFileTypeAppleM4A
    assetExport.outputURL = fileDestinationUrl
    assetExport.exportAsynchronouslyWithCompletionHandler({
        switch assetExport.status{
        case  AVAssetExportSessionStatus.Failed:
            println("failed \(assetExport.error)")
        case AVAssetExportSessionStatus.Cancelled:
            println("cancelled \(assetExport.error)")
        default:
            println("complete")
            var audioPlayer = AVAudioPlayer()
            AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: nil)
            //audioPlayer.delegate = self

            audioPlayer = AVAudioPlayer(contentsOfURL: fileDestinationUrl, error: nil)
            println(fileDestinationUrl)
            audioPlayer.prepareToPlay()
            audioPlayer.play()
        }

    })


}

应用程序加载，一切正常，我得到了文件的 println，我得到了无文件、成功和完成的打印输出，这意味着它全部执行了。但没有声音播放

Answer 1

But no sound plays

因为audioPlayer是一个局部变量，并且在它有机会播放任何内容之前就消失了。将其提升为实例变量以使其持续存在。