如何在播放过程中改变音高？(Swift 4)

import AVFoundation

// 创建AVAudioEngine实例
let audioEngine = AVAudioEngine()

// 创建AVAudioPlayerNode实例
let audioPlayerNode = AVAudioPlayerNode()

// 创建AVAudioUnitTimePitch实例
let audioPitchUnit = AVAudioUnitTimePitch()

// 设置音高参数
audioPitchUnit.pitch = 1000 // 设置音高为1000 cents，可以根据需求调整

// 连接AVAudioPlayerNode和AVAudioUnitTimePitch到AVAudioEngine的主混音器
audioEngine.attach(audioPlayerNode)
audioEngine.attach(audioPitchUnit)
audioEngine.connect(audioPlayerNode, to: audioPitchUnit, format: nil)
audioEngine.connect(audioPitchUnit, to: audioEngine.mainMixerNode, format: nil)

// 加载音频文件到AVAudioFile实例
let audioFile = try AVAudioFile(forReading: audioURL)

// 将音频文件设置为AVAudioPlayerNode的播放文件
audioPlayerNode.scheduleFile(audioFile, at: nil)

// 启动AVAudioEngine
try audioEngine.start()

// 播放音频
audioPlayerNode.play()