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，可以播放，暂停，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，恢复，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，主要用来管理音频设置与硬件交互.关于AVAudioSession`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 = 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 = try? AVAudioPlayer(contentsOf: ringtoneUrl)
audioPlayer?.play()
}
看似一切正常，但是当你频繁的点击切换ringtone,变成开始，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，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，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，这里推荐Queue来控制，因为Queue api比较友好，并且比较可控.
//作为一个对象的变量比较好，因为会多次点击播放，这样用同一个queue管理.
lazy var ringToneQueue: OperationQueue = {
let ringToneQueue = OperationQueue()
ringToneQueue.name = "rc.ringtone.queue"
ringToneQueue.maxConcurrentOperationCount = 1
return 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，不会多次创建AVAudioPlayer。
internal class AudioPlayerManager : NSObject {
internal static let shared: AudioPlayerManager
internal var currentTime: TimeInterval? { get set }
internal var audioFilePath: String? { get }
internal var isPlaying: Bool { get }
internal var delegates: <<error type>>
override internal init()
internal func setCategory(category: AVAudioSession.Category, options: AVAudioSession.CategoryOptions, shouldSetPlayBack: Bool = true) throws
/**
* Prepare some configuration for AudioPlayer.
* Call this method to configurate AudioPlayer and than call `play(atTime time: TimeInterval? = nil)` to play audio.
*
*/
internal func configAudioPlayer(with audioFilePath: String, configAudioPlayerClosure: ((Bool, Error?) -> Void)?)
/**
*
* Call this method after call `configAudioPlayer(with audioFilePath: String, configAudioPlayerClosure: ((AVAudioPlayer?) -> Void)?)`.
*
*/
internal func play(category: AVAudioSession.Category = .playAndRecord, options: AVAudioSession.CategoryOptions = [.defaultToSpeaker], portOverride: AVAudioSession.PortOverride = .none) throws
internal func play(audioFilePath: String, category: AVAudioSession.Category = .playAndRecord, options: AVAudioSession.CategoryOptions = [.defaultToSpeaker], atTime time: TimeInterval? = nil, portOverride: AVAudioSession.PortOverride = .none) throws
internal func stop(options: AVAudioSession.SetActiveOptions = [.notifyOthersOnDeactivation])
internal func pause(options: AVAudioSession.SetActiveOptions = [.notifyOthersOnDeactivation])
internal func resume()
internal func setAudioSessionActive(isActive: Bool, options: AVAudioSession.SetActiveOptions = [])
}
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ringtone
if !AudioPlayerManager.shared.isPlaying {
AudioPlayerManager.play(audioFilePath: selectedTonePath)
} else {
if let path = AudioPlayerManager.audioFilePath, path == selectedTonePath {
AudioPlayerManager.stop()
} else {
AudioPlayerManager.play(audioFilePath: selectedTonePath)
}
}
})
