消除强制展开的最佳方法

您可以使用的第一个 if let (或者 guard let ):

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

在第二个示例中,我将使用默认值:

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

但是,我看到您已经在使用 如果让 在第二种情况下,你不需要这个。所以我认为最好是 如果让 在这两种情况下,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,如@Fogmaster所述,使用 guard 在第二种方法中,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
        })
    })
}

你可以 recorder 而是懒惰。

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