Swift：主界面冻结即使一切都在asynchronous线程？ URLsession？

我仍然得到了asynchronous/后台线程的挂钩，但我不知道什么是这个调用。 基本上我正在build立一个播客播放器，在一个URLSession中从一个RSS feed中传输audiom4as。

我的问题是尽pipe把所有我能想到的，尤其是实际的AudioPlayerManager.shared.play(asynchronousfunc，UIbutton仍然冻结时，轨道是“初始化”，意思是试图播放。这是一个问题，因为它冻结整个应用程序，如果这些糟糕的连接，或者你有什么 – 这个UI挂起总是会发生，但是不同的时间，即使RSS提要没有时间parsing，没有挂起。

我正在使用GitHub库（ https://github.com/tschob/AudioPlayerManager ）来执行此操作。 这里是我每次查看（它的一个标签栏VC选项卡）出现的代码，它调用startup funcasynchronous：

 override func viewDidAppear(_ animated: Bool) { { //these should always happen, MUST BE in view did appear loadIndicator.isHidden = false overallNavigator.animateMediaBar(inPos: false) if(originalUrl != currentTrackUrl) //new m4a { print("NEW TRACK") trackStatus = .Initializing playModeStreaming = true } if(adURL == "" || adURL == nil) { adURL = "http://www.adventuresindesignmarket.com" } updateLoader() //print("EQUALS: The public var: ", currentTrackUrl," |From podcast VC:", originalUrl, "| Bool: ", originalUrl == currentTrackUrl) printToConsole = true //will disable load too print("download url: ", downloadUrl, " | path: ", pathUrl) //------------------------------------- setAllDownloadedUrls() //Must be async DispatchQueue.global(qos: .background).async { [weak self] () -> Void in guard let strongSelf = self else { return } DispatchQueue.main.async(execute: { () -> Void in if(currentTrackUrl != strongSelf.originalUrl) //new m4a { AudioPlayerManager.shared.play(urlString: strongSelf.urlStr) //must be here strongSelf.startUp() } else if(strongSelf.trackStatus == .Initializing || strongSelf.trackStatus == .Ready) { //was already playing strongSelf.startUp() } }) } } 

然后在启动我再次asynchronous启动计时器连续运行，以确保所有的用户界面是正确的跟踪标题和所有，等我不包括计时器，因为它只是很多代码可能会令人困惑，但如果我是正确的Id认为，因为定时器是asynchronous设置的，应该在计时器中的每一个asynchronous？ ：

 //INITIAL setup func startUp() { if(AudioPlayerManager.shared.isPlaying()) { trackLength = (AudioPlayerManager.shared.currentTrack?.durationInSeconds())! var timeProgressed = trackLength-((AudioPlayerManager.shared.currentTrack?.currentProgress())!*trackLength) hmsFrom(seconds: Int(timeProgressed)) { h, m, s in let hours = self.getStringFrom(seconds: h) let minutes = self.getStringFrom(seconds: m) let seconds = self.getStringFrom(seconds: s) if(h != 0) { self.trackTimeStr = "\(hours):\(minutes):\(seconds)" } else { self.trackTimeStr = "\(minutes):\(seconds)" } } timeLabel.text = trackTimeStr trackLabelLabel.text = trackLabel if(adURL == "" || adURL == nil) { adURL = "http://www.adventuresindesignmarket.com" } if let artWork = AudioPlayerManager.shared.currentTrack?.nowPlayingInfo?[MPMediaItemPropertyArtwork] as? MPMediaItemArtwork { trackImg = artWork.image(at: CGSize(width: 1100, height: 1100))! imgView.image = trackImg } } //async set timer DispatchQueue.global(qos: .background).async { [weak self] () -> Void in guard let strongSelf = self else { return } DispatchQueue.main.async { () -> Void in strongSelf.setTimer() } } //setup--------------------------- AudioPlayerManager.shared.addPlayStateChangeCallback(self, callback: { [weak self] (track: AudioTrack?) in if(track != nil) { //print("change "+AudioPlayerManager.shared.playerStateChangedNotificationKey(track: track!)) } }) // Listen to the playback time changed. Thirs event occurs every `AudioPlayerManager.PlayingTimeRefreshRate` seconds. AudioPlayerManager.shared.addPlaybackTimeChangeCallback(self, callback: { [weak self] (track: AudioTrack?) in }) } 

为什么这会导致我的应用程序用户界面挂起，如果我把它全部在asynchronous？ 我不知道在哪里转。

下面是我没有碰过的GitHub的AudioPlayerManager类：

 // // AudioPlayerManager.swift // AudioPlayerManager // // Created by Hans Seiffert on 02.08.16. // Copyright © 2016 Hans Seiffert. All rights reserved. // import Foundation import AVFoundation import MediaPlayer open class AudioPlayerManager: NSObject { // MARK: - PUBLIC - // MARK: - Properties open static let shared = AudioPlayerManager() // MARK: - Configuration /// Set this to true if the `AudioPlayerManager` log should be enabled. The default is `false`. open static var verbose = true /// Set this to true if the `AudioPlayerManager` log should contain detailed information about the calling class, function and line. The default is `true` open static var detailedLog = true /// Set this to true to use the systems `MPNowPlayingInfoCenter` (control center and lock screen). The default value is `true`. open var useNowPlayingInfoCenter = true // Set this to true to receive control events open var useRemoteControlEvents = true { didSet { self.setupRemoteControlEvents() } } // The `NSTimeInterval` of the players update interval. Eg. the PlaybackTimeChangeCallbacks will be called then. open var playingTimeRefreshRate : TimeInterval = 0.1 open var currentTrack : AudioTrack? { return self.queue.currentTrack } // MARK: - Initializaiton open class func makeStandalonePlayer() -> AudioPlayerManager { return self.makeStandalonePlayer(useNowPlayingInfoCenter: nil, useRemoteControlEvents: nil) } open class func makeStandalonePlayer(useNowPlayingInfoCenter: Bool?, useRemoteControlEvents: Bool?) -> AudioPlayerManager { let manager = AudioPlayerManager() if let _useRemoteControlEvents = useRemoteControlEvents { manager.useRemoteControlEvents = _useRemoteControlEvents } if let _useNowPlayingInfoCenter = useNowPlayingInfoCenter { manager.useNowPlayingInfoCenter = _useNowPlayingInfoCenter } return manager } public override init() { super.init() NotificationCenter.default.addObserver(self, selector: #selector(AudioPlayerManager.trackDidFinishPlaying), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: nil) } open func setup() { self.setupRemoteControlEvents() self.setupAudioSession() } // MARK: - Control playback open func togglePlayPause() { if self.isPlaying() == true { self.pause() } else { self.play() } } // MARK: Play open func canPlay() -> Bool { return self.queue.count() > 0 } open func play(updateNowPlayingInfo: Bool = false) { if let _player = self.player { _player.play() if (updateNowPlayingInfo == true || self.didStopPlayback == true) { self.updateNowPlayingInfoIfNeeded() } self.didStopPlayback = false self.startPlaybackTimeChangeTimer() self.callPlayStateChangeCallbacks() if let _currentTrack = self.currentTrack { NotificationCenter.default.post(name: Notification.Name(rawValue: self.playerStateChangedNotificationKey(track: _currentTrack)), object: nil) } } } open func play(_ audioTrack: AudioTrack) { Log("play(audioTrack: \(audioTrack))") self.stop() self.play([audioTrack], at: 0) } open func play(_ audioTracks: [AudioTrack], at startIndex: Int) { Log("play(audioTracks: \(audioTracks.count) tracks, startIndex: \(startIndex))") self.replace(with: audioTracks, at: startIndex) // Start playing the new track self.restartCurrentTrack() } open func replace(with audioTrack: AudioTrack) { Log("replace(audioTrack: \(audioTrack))") self.replace(with: [audioTrack], at: 0) } open func replace(with audioTracks: [AudioTrack], at startIndex: Int) { Log("replace(audioTracks: \(audioTracks.count) tracks, startIndex: \(startIndex))") self.stop() var reducedTracks = [] as [AudioTrack] for index in 0..<audioTracks.count { let audioTrack = audioTracks[index] reducedTracks.append(audioTrack) } self.queue.replace(reducedTracks, at: startIndex) self.queueGeneration += 1 } open func prepend(_ audioTracks: [AudioTrack], toQueue generation: Int) { if (self.queueGeneration == generation) { Log("Queue generation (\(generation)) gets prepended with \(audioTracks.count) tracks.") self.queue.prepend(audioTracks) self.callPlayStateChangeCallbacks() } else { Log("Queue generation (\(generation)) isn't the same as the current (\(self.queueGeneration)). Won't prepend \(audioTracks.count) tracks.") } } open func append(_ audioTracks: [AudioTrack], toQueue generation: Int) { if (self.queueGeneration == generation) { Log("Queue generation (\(generation)) gets appended with \(audioTracks.count) tracks.") self.queue.append(audioTracks) self.callPlayStateChangeCallbacks() } else { Log("Queue generation (\(generation)) isn't the same as the current (\(self.queueGeneration)). Won't append \(audioTracks.count) tracks.") } } // MARK: Pause open func pause() { if let _player = self.player { _player.pause() self.stopPlaybackTimeChangeTimer = true self.callPlaybackTimeChangeCallbacks() self.callPlayStateChangeCallbacks() if let _currentTrack = self.currentTrack { NotificationCenter.default.post(name: Notification.Name(rawValue: self.playerStateChangedNotificationKey(track: _currentTrack)), object: nil) } } } open func stop(clearQueue: Bool = false) { if (self.didStopPlayback == false) { self.didStopPlayback = true if (clearQueue == true) { self.clearQueue() } else { self.player?.seek(to: CMTimeMake(0, 1)) self.pause() } self.callPlayStateChangeCallbacks() self.callPlaybackTimeChangeCallbacks() } else if (clearQueue == true) { self.clearQueue() } } // MARK: Forward open func canForward() -> Bool { return self.queue.canForward() } open func forward() { self.stop() if (self.queue.forward() == true) { self.restartCurrentTrack() } } // MARK: Rewind open func canRewind() -> Bool { guard let _currentTrack = self.currentTrack else { return false } if ((_currentTrack.currentTimeInSeconds() > Float(1)) || self.canRewindInQueue()) { return true } return false } open func rewind() { guard let _currentTrack = self.currentTrack else { self.stop() return } if (_currentTrack.currentTimeInSeconds() <= Float(1) && self.canRewindInQueue() == true) { self.stop() if (self.queue.rewind() == true) { self.restartCurrentTrack() } } else { // Move to the beginning of the track if we aren't in the beginning. self.player?.seek(to: CMTimeMake(0, 1)) // Update the now playing info to show the new playback time self.updateNowPlayingInfoIfNeeded() // Call the callbacks to inform about the new time self.callPlaybackTimeChangeCallbacks() } } open func seek(toTime time: CMTime) { self.player?.seek(to: time) } open func seek(toProgress progress: Float) { let progressInSeconds = Int64(progress * (self.currentTrack?.durationInSeconds() ?? 0)) let time = CMTimeMake(progressInSeconds, 1) self.seek(toTime: time) } // MARK: - Internal helper open func trackDidFinishPlaying() { self.forward() } override open func observeValue(forKeyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) { if (object as? NSObject == self.player) { if (forKeyPath == Keys.Status) { if self.player?.status == AVPlayerStatus.readyToPlay { self.play(updateNowPlayingInfo: true) } } } } // MARK: - Playback time change callback open func addPlaybackTimeChangeCallback(_ sender: AnyObject, callback: @escaping (_ track: AudioTrack) -> Void) { let uid = "\(Unmanaged.passUnretained(sender).toOpaque())" if var _callbacks = self.playbackPositionChangeCallbacks[uid] { _callbacks.append(callback) } else { self.playbackPositionChangeCallbacks[uid] = [callback] } } open func removePlaybackTimeChangeCallback(_ sender: AnyObject) { let uid = "\(Unmanaged.passUnretained(sender).toOpaque())" self.playbackPositionChangeCallbacks.removeValue(forKey: uid) } // MARK: - Play state change callback open func addPlayStateChangeCallback(_ sender: AnyObject, callback: @escaping (_ track: AudioTrack?) -> Void) { let uid = "\(Unmanaged.passUnretained(sender).toOpaque())" if var _callbacks = self.playStateChangeCallbacks[uid] { _callbacks.append(callback) } else { self.playStateChangeCallbacks[uid] = [callback] } } open func removePlayStateChangeCallback(_ sender: AnyObject) { let uid = "\(Unmanaged.passUnretained(sender).toOpaque())" self.playStateChangeCallbacks.removeValue(forKey: uid) } // MARK: - Helper open func isPlaying() -> Bool { guard let _player = self.player else { return false } return _player.rate > 0 } // MARK: - INTERNAL - // MARK: - Properties var queueGeneration = 0 // MARK: - Initializaiton deinit { NotificationCenter.default.removeObserver(self) } func applicationDidEnterBackground(_ notification: Notification) { if (self.isPlaying() == false) { self.stop() } } // MARK: - Lifecycle func didUpdateMetadata() { self.callPlayStateChangeCallbacks() } // MARK: - PRIVATE - // MARK: - Properties fileprivate struct Keys { static let Status = "status" } fileprivate let audioPlayerManagerStateChangedPrefix = "AudioPlayerManager.\(UUID().uuidString).playerStateChanged" fileprivate var player : AVPlayer? fileprivate var queue = AudioTracksQueue() fileprivate var didStopPlayback = false // MARK: Callbacks fileprivate var playStateChangeCallbacks = Dictionary<String, [((_ track: AudioTrack?) -> (Void))]>() fileprivate var playbackPositionChangeCallbacks = Dictionary<String, [((_ track: AudioTrack) -> (Void))]>() fileprivate var playbackPositionChangeTimer : Timer? fileprivate var stopPlaybackTimeChangeTimer = false fileprivate var addedPlayerStateObserver = false // MARK: - Initializaiton fileprivate func setupAudioSession() { let _ = try? AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback) let _ = try? AVAudioSession.sharedInstance().setActive(true) } fileprivate func initPlayer() { if let _player = self.player { _player.addObserver(self, forKeyPath: Keys.Status, options: NSKeyValueObservingOptions.new, context: nil) self.addedPlayerStateObserver = true } if (self.player?.responds(to: #selector(setter: AVAudioMixing.volume)) == true) { self.player?.volume = 1.0 } self.player?.allowsExternalPlayback = true self.player?.usesExternalPlaybackWhileExternalScreenIsActive = true } fileprivate func setupRemoteControlEvents() { if (self.useRemoteControlEvents == true) { UIApplication.shared.beginReceivingRemoteControlEvents() } else { UIApplication.shared.endReceivingRemoteControlEvents() } } // MARK: - Play fileprivate func restartCurrentTrack() { Log("restartCurrentTrack") if (self.player != nil) { if (self.addedPlayerStateObserver == true) { self.addedPlayerStateObserver = false self.player?.removeObserver(self, forKeyPath: Keys.Status, context: nil) } self.stop() } if let _currentTrack = self.queue.currentTrack { self.player = AVPlayer() self.initPlayer() _currentTrack.loadResource() if let _playerItem = _currentTrack.getPlayerItem() { _currentTrack.prepareForPlaying(_playerItem) self.player?.replaceCurrentItem(with: _playerItem) } } } // MARK: Rewind fileprivate func canRewindInQueue() -> Bool { return self.queue.canRewind() } // MARK: - Internal helper fileprivate func updateNowPlayingInfoIfNeeded() { if (self.useNowPlayingInfoCenter == true) { // Update the current play time self.currentTrack?.updateNowPlayingInfoPlaybackTime() MPNowPlayingInfoCenter.default().nowPlayingInfo = self.currentTrack?.nowPlayingInfo } } private func clearQueue() { self.queue.replace(nil, at: 0) self.queueGeneration += 1 self.player?.replaceCurrentItem(with: nil) } // MARK: - Plaback time change callback func callPlaybackTimeChangeCallbacks() { self.updateNowPlayingInfoIfNeeded() // Increase the current tracks playing time if the player is playing if let _currentTrack = self.currentTrack { for sender in self.playbackPositionChangeCallbacks.keys { if let _callbacks = self.playbackPositionChangeCallbacks[sender] { for playbackPositionChangeClosure in _callbacks { playbackPositionChangeClosure(_currentTrack) } } } } if (self.stopPlaybackTimeChangeTimer == true) { self.playbackPositionChangeTimer?.invalidate() } } fileprivate func startPlaybackTimeChangeTimer() { self.stopPlaybackTimeChangeTimer = false self.playbackPositionChangeTimer = Timer.scheduledTimer(timeInterval: self.playingTimeRefreshRate, target: self, selector: #selector(AudioPlayerManager.callPlaybackTimeChangeCallbacks), userInfo: nil, repeats: true) self.playbackPositionChangeTimer?.fire() } // MARK: - Play state change callback func callPlayStateChangeCallbacks() { for sender in self.playStateChangeCallbacks.keys { if let _callbacks = self.playStateChangeCallbacks[sender] { for playStateChangeClosure in _callbacks { playStateChangeClosure(self.currentTrack) } } } } } extension AudioPlayerManager { public func playerStateChangedNotificationKey(track: AudioTrack) -> String { return "\(self.audioPlayerManagerStateChangedPrefix)_\(track.identifier() ?? "")" } }