消除强制展开的最佳方法

Question

var recorder : Recorder? = nil

func startAudioRecording() {
    if recorder == nil {
        recorder = Recorder()
    }
    if !recorder!.isRunning() {
        recorder?.startRecording({ [weak self] audioData in
            self?.remoteInterface?.sendVoice(audioData.0)
        }, withCompletionBlock: { (_) in })
    }
}

func stopAudioRecording(_ keyCommand: String!){
    if let _ = recorder {
        if(recorder?.isRunning())! {
            recorder?.stopRecording(completionBlock: { (isFinished: Bool) in
                DispatchQueue.global().asyncAfter(deadline: DispatchTime.now() + Double(Int64(1 * NSEC_PER_MSEC)) / Double(NSEC_PER_SEC), execute: { [unowned self] in
                    self.remoteInterface?.sendTouchUp(keyCommand)
                    self.audioRecorder = nil
                })
            })
        }
    }
}

我们如何去除强制展开？

Answer 1

您可以使用 if let（或者 guard let）处理的第一个问题：

if let recorder = recorder {
    // here it is unwrapped
} else {
    // handle nil case
}

在第二个中我会使用默认值：

if (recorder?.isRunning() ?? false) {
    // ...
}

但是，我看到您已经在第二种情况下使用了 if let，因此您不需要它。所以我认为在这两种情况下最好使用 if let，所以可能是这样的：

var recorder : Recorder? = nil

func startAudioRecording(){
    if recorder == nil {
        recorder = Recorder()
    }
    if let recorder = recorder,
        !recorder.isRunning() {

        recorder.startRecording({ [weak self] audioData in
            self?.remoteInterface?.sendVoice(audioData.0)
        }, withCompletionBlock: { (_) in })
    }
}

func stopAudioRecording(_ keyCommand: String!){
    if let recorder = recorder,
        recorder.isRunning() {

        recorder.stopRecording(completionBlock: { (isFinished: Bool) in
            DispatchQueue.global().asyncAfter(deadline: DispatchTime.now() + Double(Int64(1 * NSEC_PER_MSEC)) / Double(NSEC_PER_SEC), execute: { [unowned self] in
                self.remoteInterface?.sendTouchUp(keyCommand)
                self.audioRecorder = nil
            })
        })
    }
}

或者，正如@Fogmaster 指出的那样，在第二种方法中使用 guard 可能看起来更好一些：

func stopAudioRecording(_ keyCommand: String!){
    guard let recorder = recorder,
        recorder.isRunning() else {
        return
    }

    recorder.stopRecording(completionBlock: { (isFinished: Bool) in
        DispatchQueue.global().asyncAfter(deadline: DispatchTime.now() + Double(Int64(1 * NSEC_PER_MSEC)) / Double(NSEC_PER_SEC), execute: { [unowned self] in
            self.remoteInterface?.sendTouchUp(keyCommand)
            self.audioRecorder = nil
        })
    })
}

Answer 2

你可以让 recorder 变得懒惰。

var recorder: Recorder = {
    return Recorder()
}()

消除强制展开的最佳方法

Best way to remove force unwrapping

optional

ios

swift

forceunwrap