Ios AVURLAsset当响应不响应时'；我没有'；内容长度'；标题

我的iOS应用程序使用AVPlayer播放来自我的服务器的流式音频，并将其存储在设备上。 我实现了AVAssetResourceLoaderDelegate，因此可以拦截流。我将方案（从

http

更改为假方案，以便调用AVAssetResourceLoaderDelegate方法：

func resourceLoader（resourceLoader:AVAssetResourceLoader，shouldWaitForLoadingFrequestEndResource loadingRequest:AVAssetResourceLoadingRequest）->Bool

我遵循了本教程：

在那里，我把原来的方案放回原处，并创建了一个从服务器中提取音频的会话。当我的服务器为流式音频文件提供

内容长度

（音频文件的大小以字节为单位）头时，一切都能完美地工作

但有时我会在无法提前提供长度的情况下传输音频文件（比如实时播客流）。在这种情况下，AVURLAsset会将长度设置为

-1

，并在以下情况下失败：

“Error Domain=AVFoundationErrorDomain code=-11849\”操作已停止\“UserInfo={NSUnderlyingError=0x6180004abc0{Error Domain=nsossstatuserrordomain code=-12873\”（null）\”，NSLocalizedFailureReason=此媒体可能已损坏，NSLocalizedDescription=操作已停止}

我无法绕过这个错误。我试图用一种不正当的方式，提供虚假信息

内容长度：99999999

，但在这种情况下，一旦下载了整个音频流，我的会话将失败，原因是：

到目前为止已加载：9999999中有10349852个
请求超时。
//已下载音频文件，其大小为10349852
//AVPlayer尝试获取下一个区块，但由于请求超时而失败

以前有人遇到过这个问题吗

另外，如果我在avurlaste中保留原始的

http

方案，AVPlayer知道如何处理该方案，因此它可以播放音频文件（即使没有

内容长度

），我不知道它是如何在没有失败的情况下运行的。此外，在这种情况下，我的AVAssetResourceLoaderDelegate从未使用过，因此我无法截取音频文件的内容并将其复制到本地存储

以下是实施方案：

import AVFoundation

@objc protocol CachingPlayerItemDelegate {

    // called when file is fully downloaded
    @objc optional func playerItem(playerItem: CachingPlayerItem, didFinishDownloadingData data: NSData)

    // called every time new portion of data is received
    @objc optional func playerItemDownloaded(playerItem: CachingPlayerItem, didDownloadBytesSoFar bytesDownloaded: Int, outOf bytesExpected: Int)

    // called after prebuffering is finished, so the player item is ready to play. Called only once, after initial pre-buffering
    @objc optional func playerItemReadyToPlay(playerItem: CachingPlayerItem)

    // called when some media did not arrive in time to continue playback
    @objc optional func playerItemDidStopPlayback(playerItem: CachingPlayerItem)

    // called when deinit
    @objc optional func playerItemWillDeinit(playerItem: CachingPlayerItem)

}

extension URL {

    func urlWithCustomScheme(scheme: String) -> URL {
        var components = URLComponents(url: self, resolvingAgainstBaseURL: false)
        components?.scheme = scheme
        return components!.url!
    }

}

class CachingPlayerItem: AVPlayerItem {

    class ResourceLoaderDelegate: NSObject, AVAssetResourceLoaderDelegate, URLSessionDelegate, URLSessionDataDelegate, URLSessionTaskDelegate {

        var playingFromCache = false
        var mimeType: String? // is used if we play from cache (with NSData)

        var session: URLSession?
        var songData: NSData?
        var response: URLResponse?
        var pendingRequests = Set<AVAssetResourceLoadingRequest>()
        weak var owner: CachingPlayerItem?

        //MARK: AVAssetResourceLoader delegate

        func resourceLoader(_ resourceLoader: AVAssetResourceLoader, shouldWaitForLoadingOfRequestedResource loadingRequest: AVAssetResourceLoadingRequest) -> Bool {

            if playingFromCache { // if we're playing from cache
                // nothing to do here
            } else if session == nil { // if we're playing from url, we need to download the file
                let interceptedURL = loadingRequest.request.url!.urlWithCustomScheme(scheme: owner!.scheme!).deletingLastPathComponent()
                startDataRequest(withURL: interceptedURL)
            }

            pendingRequests.insert(loadingRequest)
            processPendingRequests()
            return true
        }

        func startDataRequest(withURL url: URL) {
            let request = URLRequest(url: url)
            let configuration = URLSessionConfiguration.default
            configuration.requestCachePolicy = .reloadIgnoringLocalAndRemoteCacheData
            configuration.timeoutIntervalForRequest = 60.0
            configuration.timeoutIntervalForResource = 120.0
            session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
            let task = session?.dataTask(with: request)
            task?.resume()
        }

        func resourceLoader(_ resourceLoader: AVAssetResourceLoader, didCancel loadingRequest: AVAssetResourceLoadingRequest) {
            pendingRequests.remove(loadingRequest)
        }

        //MARK: URLSession delegate

        func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
            (songData as! NSMutableData).append(data)
            processPendingRequests()
            owner?.delegate?.playerItemDownloaded?(playerItem: owner!, didDownloadBytesSoFar: songData!.length, outOf: Int(dataTask.countOfBytesExpectedToReceive))
        }

        func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: @escaping (URLSession.ResponseDisposition) -> Void) {
            completionHandler(URLSession.ResponseDisposition.allow)
            songData = NSMutableData()
            self.response = response
            processPendingRequests()
        }

        func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError err: Error?) {
            if let error = err {
                print(error.localizedDescription)
                return
            }
            processPendingRequests()
            owner?.delegate?.playerItem?(playerItem: owner!, didFinishDownloadingData: songData!)
        }

        //MARK:

        func processPendingRequests() {
            var requestsCompleted = Set<AVAssetResourceLoadingRequest>()
            for loadingRequest in pendingRequests {
                fillInContentInforation(contentInformationRequest: loadingRequest.contentInformationRequest)
                let didRespondCompletely = respondWithDataForRequest(dataRequest: loadingRequest.dataRequest!)
                if didRespondCompletely {
                    requestsCompleted.insert(loadingRequest)
                    loadingRequest.finishLoading()
                }
            }
            for i in requestsCompleted {
                pendingRequests.remove(i)
            }
        }

        func fillInContentInforation(contentInformationRequest: AVAssetResourceLoadingContentInformationRequest?) {
            // if we play from cache we make no URL requests, therefore we have no responses, so we need to fill in contentInformationRequest manually
            if playingFromCache {
                contentInformationRequest?.contentType = self.mimeType
                contentInformationRequest?.contentLength = Int64(songData!.length)
                contentInformationRequest?.isByteRangeAccessSupported = true
                return
            }

            // have no response from the server yet
            if  response == nil {
                return
            }

            let mimeType = response?.mimeType
            contentInformationRequest?.contentType = mimeType
            if response?.expectedContentLength != -1 {
                contentInformationRequest?.contentLength = response!.expectedContentLength
                contentInformationRequest?.isByteRangeAccessSupported = true
            } else {
                contentInformationRequest?.isByteRangeAccessSupported = false
            }
        }

        func respondWithDataForRequest(dataRequest: AVAssetResourceLoadingDataRequest) -> Bool {

            let requestedOffset = Int(dataRequest.requestedOffset)
            let requestedLength = dataRequest.requestedLength
            let startOffset = Int(dataRequest.currentOffset)

            // Don't have any data at all for this request
            if songData == nil || songData!.length < startOffset {
                return false
            }

            // This is the total data we have from startOffset to whatever has been downloaded so far
            let bytesUnread = songData!.length - Int(startOffset)

            // Respond fully or whaterver is available if we can't satisfy the request fully yet
            let bytesToRespond = min(bytesUnread, requestedLength + Int(requestedOffset))
            dataRequest.respond(with: songData!.subdata(with: NSMakeRange(startOffset, bytesToRespond)))

            let didRespondFully = songData!.length >= requestedLength + Int(requestedOffset)
            return didRespondFully

        }

        deinit {
            session?.invalidateAndCancel()
        }

    }

    private var resourceLoaderDelegate = ResourceLoaderDelegate()
    private var scheme: String?
    private var url: URL!

    weak var delegate: CachingPlayerItemDelegate?

    // use this initializer to play remote files
    init(url: URL) {

        self.url = url

        let components = URLComponents(url: url, resolvingAgainstBaseURL: false)!
        scheme = components.scheme

        let asset = AVURLAsset(url: url.urlWithCustomScheme(scheme: "fakeScheme").appendingPathComponent("/test.mp3"))
        asset.resourceLoader.setDelegate(resourceLoaderDelegate, queue: DispatchQueue.main)
        super.init(asset: asset, automaticallyLoadedAssetKeys: nil)
        resourceLoaderDelegate.owner = self

        self.addObserver(self, forKeyPath: "status", options: NSKeyValueObservingOptions.new, context: nil)

        NotificationCenter.default.addObserver(self, selector: #selector(didStopHandler), name:NSNotification.Name.AVPlayerItemPlaybackStalled, object: self)

    }

    // use this initializer to play local files
    init(data: NSData, mimeType: String, fileExtension: String) {

        self.url = URL(string: "whatever://whatever/file.\(fileExtension)")

        resourceLoaderDelegate.songData = data
        resourceLoaderDelegate.playingFromCache = true
        resourceLoaderDelegate.mimeType = mimeType

        let asset = AVURLAsset(url: url)
        asset.resourceLoader.setDelegate(resourceLoaderDelegate, queue: DispatchQueue.main)

        super.init(asset: asset, automaticallyLoadedAssetKeys: nil)
        resourceLoaderDelegate.owner = self

        self.addObserver(self, forKeyPath: "status", options: NSKeyValueObservingOptions.new, context: nil)

        NotificationCenter.default.addObserver(self, selector: #selector(didStopHandler), name:NSNotification.Name.AVPlayerItemPlaybackStalled, object: self)

    }

    func download() {
        if resourceLoaderDelegate.session == nil {
            resourceLoaderDelegate.startDataRequest(withURL: url)
        }
    }

    override init(asset: AVAsset, automaticallyLoadedAssetKeys: [String]?) {
        fatalError("not implemented")
    }

    // MARK: KVO
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        delegate?.playerItemReadyToPlay?(playerItem: self)
    }

    // MARK: Notification handlers

    func didStopHandler() {
        delegate?.playerItemDidStopPlayback?(playerItem: self)
    }

    // MARK:

    deinit {
        NotificationCenter.default.removeObserver(self)
        removeObserver(self, forKeyPath: "status")
        resourceLoaderDelegate.session?.invalidateAndCancel()
        delegate?.playerItemWillDeinit?(playerItem: self)
    }

}

import-AVFoundation
@objc协议CachingPlayerItemDelegate{
//文件完全下载时调用
@objc可选功能playerItem（playerItem:CachingPlayerItem，didFinishDownloadingData:NSData）
//每次接收到数据的新部分时调用
@objc可选功能playerItem下载（playerItem:CachingPlayerItem，didDownloadBytesSoFar bytesDownloaded:Int，outOf bytesExpected:Int）
//在预缓冲完成后调用，因此播放器项已准备好播放。仅在初始预缓冲后调用一次
@objc可选功能playerItemReadyToPlay（playerItem:CachingPlayerItem）
//当某些媒体未及时到达以继续播放时调用
@objc可选函数playerItemDidStopPlayback（playerItem:CachingPlayerItem）
//当脱硝时被称为
@objc可选函数playerItemWillDeinit（playerItem:CachingPlayerItem）
}
扩展URL{
func urlWithCustomScheme（方案：字符串）->URL{
var components=URLComponents（url:self，resolvingAgainstBaseURL:false）
组件？.scheme=scheme
返回组件！.url！
}
}
CachingPlayerItem类：AVPlayerItem{
类ResourceLoaderDelegate:NSObject、AVAssetResourceLoaderDelegate、URLSessionDelegate、URLSessionDataDelegate、URLSessionTaskDelegate{
var playingFromCache=false
var mimeType:String？//用于从缓存播放（使用NSData）
var会话：URLSession？
数据：NSData？
var响应：URLResponse？
var pendingRequests=Set（）
弱var所有者：CachingPlayerItem？
//标记：AVAssetResourceLoader委托
func resourceLoader（resourceLoader:AVAssetResourceLoader，shouldWaitForLoadingFrequestedResource loadingRequest:AVAssetResourceLoadingRequest）->Bool{
如果从缓存播放{//如果我们从缓存播放
//这里没什么可做的
}否则，如果session==nil{//如果我们从url播放，我们需要下载文件
让interceptedURL=loadingRequest.request.url！.urlWithCustomScheme（方案：owner！.scheme！）。删除LastPathComponent（）
startDataRequest（带URL:interceptedURL）
}
pendingRequests.insert（加载请求）
processPendingRequests（）
返回真值
}
func startDataRequest（带url:url）{
let request=URLRequest（url:url）
let configuration=URLSessionConfiguration.default
configuration.requestCachePolicy=.reloadIgnoringLocalAndRemoteCacheData
configuration.timeoutitervalforrequest=60.0
configuration.timeoutitervalforresource=120.0
session=URLSession（配置：配置，委托：self，委托队列：nil）
让任务=会话？.dataTask（带：请求）
任务？.resume（）
}
func resourceLoader（resourceLoader:AVAssetResourceLoader，didCancel loadingRequest:AVAssetResourceLoadingRequest）{
pendingRequests.remove（加载请求）
}
//标记：URLSession委托
func urlSession（session:urlSession，dataTask:URLSessionDataTask，didReceive data:data）{
（songData为！NSMutableData）.append（数据）
processPendingRequests（）
owner？.delegate？.playerItemDownloaded？（playerItem:owner！，didDownloadBytesSoFar:songData！.length，outOf:Int（dataTask.countOfBytesExpectedToReceive））
}
func urlSession（session:urlSession，dataTask:URLSessionDataTask，didReceive响应：URLResponse，completionHandler:@escaping（urlSession.ResponseDisposition）->Void）{
completionHandler（URLSession.ResponseDisposition.allow）
songData=NSMutableData（）