UseAVAudioPlayerinOperationQueue

业务需求要提供一些ringtone供用户选择并且设置为来电铃声.这样就会涉及到预览ringtone.这边预览ringtone选择用AVAudioPlayer去播放.选择AVAudioPlayer的原因是AVAudioPlayer可控性比较大&＃xff0c;可以播放&＃xff0c;暂停&＃xff0c;恢复播放等.使用AudioToolbox提供的api也能播放ringtone当是不能满足操作需求,暂停&＃xff0c;恢复&＃xff0c;故排除AudioToolbox.

要使用AVAudioPlayer播放ringtone必然会涉及到AVAudioSession.AVAudioSession简而言之: 音频会话&＃xff0c;主要用来管理音频设置与硬件交互.关于AVAudioSession&＃96;详细的信息读者可自行去查.播放一个ringtone的简化流程代码大概如下:


try? AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playAndRecord)try? AVAudioSession.sharedInstance().setActive(true, options: [])let audioPlayer &＃61; try? AVAudioPlayer(contentsOf: ringtoneUrl)audioPlayer?.play()


为了不卡UI一般会放到子线程中去播放:


DispatchQueue.global().async {
try? AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playAndRecord)try? AVAudioSession.sharedInstance().setActive(true, options: [])let audioPlayer &＃61; try? AVAudioPlayer(contentsOf: ringtoneUrl)audioPlayer?.play()
}

看似一切正常&＃xff0c;但是当你频繁的点击切换ringtone,变成开始&＃xff0c;结束,暂停。这样会导致播放失败又有多线程竞争音频资源的问题&＃xff0c;并且在iOS10.x上会crash,因为音频资源不可能切换太快.并且快速切换也会开启多个子线程&＃xff0c;这是没必要的.一般来说一个设计合理的app同一时刻只会有一个音频在播放.所以我们只需要一个线程专门控制音频播放即可&＃xff0c;这里推荐Queue来控制&＃xff0c;因为Queue api比较友好&＃xff0c;并且比较可控.

//作为一个对象的变量比较好&＃xff0c;因为会多次点击播放&＃xff0c;这样用同一个queue管理.
lazy var ringToneQueue: OperationQueue &＃61; {let ringToneQueue &＃61; OperationQueue()ringToneQueue.name &＃61; "rc.ringtone.queue"ringToneQueue.maxConcurrentOperationCount &＃61; 1return ringToneQueue
}()


//回收资源
if self.ringToneQueue.operationCount > 0 {self.ringToneQueue.cancelAllOperations()
}self.ringToneQueue.addOperation({//播放ringtone
})

根据业务需求我这边是把包装AVAudioPlayer成一个单例&＃xff0c;不会多次创建AVAudioPlayer。


internal class AudioPlayerManager : NSObject {internal static let shared: AudioPlayerManagerinternal var currentTime: TimeInterval? { get set }internal var audioFilePath: String? { get }internal var isPlaying: Bool { get }internal var delegates: <>override internal init()internal func setCategory(category: AVAudioSession.Category, options: AVAudioSession.CategoryOptions, shouldSetPlayBack: Bool &＃61; true) throws/*** Prepare some configuration for AudioPlayer.* Call this method to configurate AudioPlayer and than call &＃96;play(atTime time: TimeInterval? &＃61; nil)&＃96; to play audio.**/internal func configAudioPlayer(with audioFilePath: String, configAudioPlayerClosure: ((Bool, Error?) -> Void)?)/**** Call this method after call &＃96;configAudioPlayer(with audioFilePath: String, configAudioPlayerClosure: ((AVAudioPlayer?) -> Void)?)&＃96;.**/internal func play(category: AVAudioSession.Category &＃61; .playAndRecord, options: AVAudioSession.CategoryOptions &＃61; [.defaultToSpeaker], portOverride: AVAudioSession.PortOverride &＃61; .none) throwsinternal func play(audioFilePath: String, category: AVAudioSession.Category &＃61; .playAndRecord, options: AVAudioSession.CategoryOptions &＃61; [.defaultToSpeaker], atTime time: TimeInterval? &＃61; nil, portOverride: AVAudioSession.PortOverride &＃61; .none) throwsinternal func stop(options: AVAudioSession.SetActiveOptions &＃61; [.notifyOthersOnDeactivation])internal func pause(options: AVAudioSession.SetActiveOptions &＃61; [.notifyOthersOnDeactivation])internal func resume()internal func setAudioSessionActive(isActive: Bool, options: AVAudioSession.SetActiveOptions &＃61; [])
}

这样播放的代码大概是这样:


//回收资源
if self.ringToneQueue.operationCount > 0 {self.ringToneQueue.cancelAllOperations()
}self.ringToneQueue.addOperation({//播放ringtoneif !AudioPlayerManager.shared.isPlaying {AudioPlayerManager.play(audioFilePath: selectedTonePath)} else {if let path &＃61; AudioPlayerManager.audioFilePath, path &＃61;&＃61; selectedTonePath {AudioPlayerManager.stop()} else {AudioPlayerManager.play(audioFilePath: selectedTonePath)}}
})