ios - 将完成处理程序添加到函数 swift

Question

我有这段代码，它在 Swift 中运行一个音频文件。

 func playSound(name: String) {
        DispatchQueue.global(qos: .userInteractive).async {
            guard let url = Bundle.main.url(forResource: name, withExtension: "m4a") else {return}
            do {
                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                try AVAudioSession.sharedInstance().setActive(true)

                self.player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileType.mp3.rawValue)

                guard let player = self.player else { return }
                player.play()
            } catch let error {
                print(error.localizedDescription)
            }
        }
    }

我想向这段代码添加一个完成处理程序。我该怎么做？

Answer 1

只需在声明中添加一个@escaping 参数，然后在任何你想要的地方运行完成闭包(最常见的是成功):

func playSound(name: String, completion: @escaping () -> Void) {  // <- HERE
    DispatchQueue.global(qos: .userInteractive).async {
        guard let url = Bundle.main.url(forResource: name, withExtension: "m4a") else {return}
        do {
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
            try AVAudioSession.sharedInstance().setActive(true)

            self.player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileType.mp3.rawValue)

            guard let player = self.player else { return }
            player.play()

            completion()  // <- HERE
        } catch let error {
            print(error.localizedDescription)
        }
    }
}

这样调用它:

let audioPlayer = AudioPlayer()
audioPlayer.playSound(name: "some_sound") {
    // Completion closure here gets run (given correct input)
    print("Done!")
}