要使用AVAudioEngine从网络获取数据并播放，您需要以下步骤：

1. 导入所需的框架：

import AVFoundation
import MediaPlayer

2. 创建AVAudioEngine实例并准备进行音频播放：

let audioEngine = AVAudioEngine()

3. 创建AVPlayer实例来播放网络音频：

let url = URL(string: "YOUR_AUDIO_FILE_URL")!
let playerItem = AVPlayerItem(url: url)
let player = AVPlayer(playerItem: playerItem)

4. 创建AVAudioPlayerNode实例来处理音频数据，并将其连接到AVAudioEngine的输出节点：

let audioPlayerNode = AVAudioPlayerNode()
audioEngine.attach(audioPlayerNode)
audioEngine.connect(audioPlayerNode, to: audioEngine.mainMixerNode, format: nil)

5. 定义一个闭包来从AVPlayer中获取音频样本数据并传递给AVAudioPlayerNode：

let blockSize: AVAudioFrameCount = 2048
player.addPeriodicTimeObserver(forInterval: CMTimeMake(value: 1, timescale: 100), queue: DispatchQueue.main) { time in
    guard let playerItem = self.player.currentItem else { return }
    guard playerItem.status == .readyToPlay else { return }
    
    let sampleTime = time.seconds * playerItem.assetTrack!.nominalFrameRate
    let audioTime = CMTimeMake(value: Int64(sampleTime), timescale: playerItem.assetTrack!.naturalTimeScale)
    if let sampleData = self.extractSampleData(from: playerItem, at: audioTime, blockSize: blockSize) {
        self.audioPlayerNode.scheduleBuffer(sampleData)
    }
}

6. 定义一个方法来从AVPlayerItem中提取音频样本数据：

func extractSampleData(from playerItem: AVPlayerItem, at audioTime: CMTime, blockSize: AVAudioFrameCount) -> AVAudioPCMBuffer? {
    guard let assetTrack = playerItem.assetTrack else { return nil }
    
    let outputFormat = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: assetTrack.nominalFrameRate, channels: 1, interleaved: false)
    let outputBuffer = AVAudioPCMBuffer(pcmFormat: outputFormat!, frameCapacity: blockSize)
    
    do {
        try playerItem.audioTimePitchAlgorithm = AVAudioTimePitchAlgorithm(rawValue: "Varispeed")
        try playerItem.audioTimePitchAlgorithm = AVAudioTimePitchAlgorithm(rawValue: "Spectral")
        
        try assetTrack.loadAudioSamples(at: audioTime, frameCount: blockSize, into: outputBuffer!)
        return outputBuffer
    } catch {
        print("Failed to extract sample data: \(error)")
        return nil
    }
}

7. 启动AVAudioEngine并开始播放：

do {
    try audioEngine.start()
    audioPlayerNode.play()
    player.play()
} catch {
    print("Failed to start audio engine: \(error)")
}

这样，您就可以从网络获取音频数据并使用AVAudioEngine播放。请注意，您需要将"YOUR_AUDIO_FILE_URL"替换为您自己的音频文件的URL。