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我從Udacity課程做了一個簡單的任務（Pitch Perfect）斯威夫特。聲音不第二次播放
我有一個屏幕，我錄製聲音。錄製後我保存文件並將其傳遞到第二個屏幕。
在第二個屏幕上，我有幾個播放聲音的按鈕。在那裏我有一個播放音調的功能。
事情是，當我第一次打這個功能的聲音播放，但第二次沒有聲音。
我被卡住了。
func playSoundWithPitchRate(pitch: Float) {
self.audioPlayer.stop()
self.audioEngine.stop()
self.audioEngine.reset()
let audioPlayerNode = AVAudioPlayerNode()
self.audioEngine.attachNode(audioPlayerNode)
let changePitchEffect = AVAudioUnitTimePitch()
changePitchEffect.pitch = pitch
self.audioEngine.attachNode(changePitchEffect)
self.audioEngine.connect(audioPlayerNode, to: changePitchEffect, format: nil)
self.audioEngine.connect(changePitchEffect, to: self.audioEngine.outputNode, format: nil)
let audioFileBuffer = AVAudioPCMBuffer(PCMFormat: self.audioFile.processingFormat, frameCapacity: AVAudioFrameCount(self.audioFile.length))
do{
try self.audioFile.readIntoBuffer(audioFileBuffer)
} catch let err as NSError {
print("self.audioFile.readIntoBuffer(audioFileBuffer)")
print(err.localizedDescription)
}
audioPlayerNode.scheduleBuffer(audioFileBuffer, atTime: nil, options: .Interrupts) {() -> Void in
// reminder: we're not on the main thread in here
dispatch_async(dispatch_get_main_queue()) {
self.stopPlayButton.enabled = false
self.makeSoundEffectButtonsEnabled(true)
}
}
do {
try audioEngine.start()
} catch let err as NSError {
print("audioEngine.start()")
print(err.localizedDescription)
}
audioPlayerNode.play()
}