我正在尝试访问 UIApplication.shared.statusBarOrientation但我不断收到错误 UIApplication.statusBarOrientation() must be used from main thread only :
我尝试将它和使用它的 switch 语句添加到 mainQueue 中，但这导致 return value从它包含的函数到崩溃并返回 nil 值:
DispatchQueue.main.async {
let interfaceOrientation = UIApplication.shared.statusBarOrientation
switch interfaceOrientation {
case .portrait, .portraitUpsideDown, .unknown:
videoOrientation = .portrait
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
@unknown default:
break
}
}
代码:
func videoOrientation() -> AVCaptureVideoOrientation {
var videoOrientation: AVCaptureVideoOrientation!
let orientation: UIDeviceOrientation = UIDevice.current.orientation
switch orientation {
case .faceUp, .faceDown, .unknown:
// ** I tried to add this alone to the mainQueue but the switch statement couldn't access it so then I tried to add the entire switch but that lead to the return value crashing with a nil
let interfaceOrientation = UIApplication.shared.statusBarOrientation
switch interfaceOrientation {
case .portrait, .portraitUpsideDown, .unknown:
videoOrientation = .portrait
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
@unknown default:
break
}
case .portrait, .portraitUpsideDown:
videoOrientation = .portrait
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
@unknown default:
break
}
return videoOrientation // ** crashes here **
}
当按下camerButton使用AVFoundation录制视频时，我访问返回值。 movieFileOutput对象访问此行 movieFileOutput.connection(with: AVMediaType.video)?.videoOrientation = videoOrientation() 上的 videoOrientation :
代码:
let captureSession = AVCaptureSession()
var movieFileOutput = AVCaptureMovieFileOutput()
var videoFileUrlFromCamera: URL?
func startRecording() {
if !captureSession.outputs.contains(movieFileOutput) {
return
}
// Stop recording
if movieFileOutput.isRecording {
stopMovieRecordigShowControls()
} else {
if !captureSession.outputs.contains(movieFileOutput) {
return
}
// Start recording
movieFileOutput.connection(with: AVMediaType.video)?.videoOrientation = videoOrientation()
movieFileOutput.maxRecordedDuration = maxRecordDuration()
videoFileUrlFromCamera = URL(fileURLWithPath: videoFileLocation())
if let videoFileUrlFromCamera = videoFileUrlFromCamera {
movieFileOutput.startRecording(to: videoFileUrlFromCamera, recordingDelegate: self)
}
}
}
如何解决这个问题？
更新
我还尝试将整个代码包装在 DispatchQueue 中，但出现编译错误 Cannot return expression of type () to return type AVCaptureVideoOrientation :
func videoOrientation() -> AVCaptureVideoOrientation {
DispatchQueue.main.async {
var videoOrientation: AVCaptureVideoOrientation!
let orientation: UIDeviceOrientation = UIDevice.current.orientation
switch orientation {
case .faceUp, .faceDown, .unknown:
let interfaceOrientation = UIApplication.shared.statusBarOrientation
switch interfaceOrientation {
case .portrait, .portraitUpsideDown, .unknown:
videoOrientation = .portrait
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
@unknown default:
break
}
break
case .portrait, .portraitUpsideDown:
videoOrientation = .portrait
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
@unknown default:
break
}
return videoOrientation
}
}
最佳答案
在主线程中调度其他代码使值
当您返回它时，var videoOrientation: AVCaptureVideoOrientation! 为 nil 因为 return 在 switch 之前触发，最好确保您调用整个 startRecording() > 来自主线程，例如
DispatchQueue.main.async {
self.startRecording()
}
由于权限检查的关闭在后台线程中运行，因此您需要在 DispatchQueue.main.async 内调度录音的调用
关于ios - Swift - 从主线程访问 UIApplication.shared.statusBarOrientation，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/59335158/