Swift：AVAssetResourceLoader不從URL播放音頻

Question

我正在嘗試使用AVAssetResourceLoader從URL流式傳輸一個小音頻剪輯，但是當我嘗試在控制台中打印時，我可以看到mimetype和內容被正確識別。 但是，它沒有播放音頻。 有人可以看看它，告訴我哪里出錯了。

import UIKit
import AVFoundation
import MobileCoreServices

class DetailViewController: UIViewController, AVAssetResourceLoaderDelegate, URLSessionDelegate, URLSessionDataDelegate {
var player:AVPlayer = AVPlayer()

override func viewDidLoad() {
    super.viewDidLoad()
    session = Foundation.URLSession(configuration: URLSessionConfiguration.background(withIdentifier: "ident"), delegate: self, delegateQueue: OperationQueue.main)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func doTapped(_ sender: AnyObject) {
    print("beginning")
    setupSession()

    let asset = AVURLAsset(url: URL(string: "testing-http://mp3.ffh.de/radioffh/livestream.mp3")!) // This can be replaced by any other api stream
    asset.resourceLoader.setDelegate(self, queue: DispatchQueue.main)
    let playerItem = AVPlayerItem(asset: asset)

    player = AVPlayer(playerItem: playerItem)
    player.actionAtItemEnd = AVPlayerActionAtItemEnd.none
    player.play()

    print("done")
}

@IBAction func playTapped(_ sender: AnyObject) {
    print(player.rate)
}

@IBAction func testTapped(_ sender: AnyObject) {
    print(player.currentItem?.loadedTimeRanges.first?.timeRangeValue.start.seconds)
}

func setupSession(){
    let session = AVAudioSession.sharedInstance()
    do{
        try session.setCategory(AVAudioSessionCategoryPlayback)
        try session.setActive(true)
        print("set up")
    }catch let err as NSError{
        print("error setting up session:", err)
    }
}

// RESOURCE LOADER
var request:AVAssetResourceLoadingRequest?

func resourceLoader(_ resourceLoader: AVAssetResourceLoader, shouldWaitForLoadingOfRequestedResource loadingRequest: AVAssetResourceLoadingRequest) -> Bool {
    print("lR:", loadingRequest)
    self.request = loadingRequest
    let task = session.dataTask(with: URL(string: (loadingRequest.request.url?.absoluteString.replacingOccurrences(of: "testing-", with: ""))!)!)
    task.resume()
    return true
}

// URL SESSION DATA
var session:Foundation.URLSession!

func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: @escaping (URLSession.ResponseDisposition) -> Void) {
    //print("resp:", response)
    completionHandler(.allow)
}

func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
    if let request = request, let dataRequest = request.dataRequest{
        let neededData = dataRequest.requestedLength - Int(dataRequest.currentOffset)
        print("the neededdata is \(neededData)")
        if (data.count >= neededData){
            print("finishing")
            if let contentInformationRequest = request.contentInformationRequest, let mimeType = dataTask.response?.mimeType{
                print("finishing 2:", mimeType)
                contentInformationRequest.contentLength = dataTask.countOfBytesExpectedToReceive
                if let contentType = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue(){
                    let contentType = contentType as String
                    print("finishing 3:", contentType)
                    contentInformationRequest.contentType = contentType
                    contentInformationRequest.isByteRangeAccessSupported = true
                }
            }
          dataRequest.respond(with: data.subdata(in: 0..<neededData+1))

            dataTask.cancel()
            request.finishLoading()
            self.request = nil
        }else{
            dataRequest.respond(with: data)
        }
    }
}
}

我們是否也按照相同的流程從帶有標題的網址流式傳輸視頻？

提前致謝

Answer 1

您不應將以下代碼放在urlseesion dataReceive數據函數中：

dataTask.cancel()
request.finishingloading()
self.request = nil

`他們將停止請求工作並阻止您接收更多數據。