在iOS中检测相机的权限

我开发了一个非常简单的video应用程序。 我使用官方控件：UIImagePickerController。

这是问题。 当第一次展示UIImagePickerController时，iOS会询问权限。 用户可以点击是或否。 如果用户点击否，控制不会被解除。 相反，如果用户不断点击开始button，定时器将继续，而屏幕始终是黑色的，用户不能停止定时器或返回。 用户唯一能做的就是杀死应用程序。 UIImagePickerController下一次出现时，它仍然是一个黑屏，如果点击开始，用户不能返回。

我想知道这是否是一个错误。 有什么办法可以检测到相机的权限，以便我们可以决定显示UIImagePickerController吗？

Answer 1

检查AVAuthorizationStatus并正确处理这些情况。

 NSString *mediaType = AVMediaTypeVideo; AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType]; if(authStatus == AVAuthorizationStatusAuthorized) { // do your logic } else if(authStatus == AVAuthorizationStatusDenied){ // denied } else if(authStatus == AVAuthorizationStatusRestricted){ // restricted, normally won't happen } else if(authStatus == AVAuthorizationStatusNotDetermined){ // not determined?! [AVCaptureDevice requestAccessForMediaType:mediaType completionHandler:^(BOOL granted) { if(granted){ NSLog(@"Granted access to %@", mediaType); } else { NSLog(@"Not granted access to %@", mediaType); } }]; } else { // impossible, unknown authorization status } 

Answer 2

从iOS 10开始，您需要在Info.plist中指定NSCameraUsageDescription键，以便能够请求相机访问，否则您的应用程序将在运行时崩溃。 请参阅API要求使用说明 。

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确保：

 import AVFoundation 

下面的Swift代码检查所有可能的权限状态：

斯威夫特3，4

 let cameraMediaType = AVMediaTypeVideo let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatus(forMediaType: cameraMediaType) switch cameraAuthorizationStatus { case .denied: break case .authorized: break case .restricted: break case .notDetermined: // Prompting user for the permission to use the camera. AVCaptureDevice.requestAccess(forMediaType: cameraMediaType) { granted in if granted { print("Granted access to \(cameraMediaType)") } else { print("Denied access to \(cameraMediaType)") } } } 

Swift 2.2

 let cameraMediaType = AVMediaTypeVideo let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatusForMediaType(cameraMediaType) switch cameraAuthorizationStatus { case .Denied: break case .Authorized: break case .Restricted: break case .NotDetermined: // Prompting user for the permission to use the camera. AVCaptureDevice.requestAccessForMediaType(cameraMediaType) { granted in if granted { print("Granted access to \(cameraMediaType)") } else { print("Denied access to \(cameraMediaType)") } } } 

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作为一个有趣的方面说明，你知道，如果iOS在应用程序中更改摄像头权限时正在运行，它将会终止应用程序？

从Apple开发者论坛：

如果用户在“设置”中切换应用对相机的访问权限，系统实际上会杀死您的应用。 这同样适用于Settings-> Privacy部分中的任何受保护的dataclass。

Answer 3

作为@Raptor答案的补充，应该提到以下内容。 从iOS 10开始，您可能会收到以下错误： This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes. This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.

要解决这个问题，请确保您按照以下方式处理主线程的结果（Swift 3）：

 private func showCameraPermissionPopup() { let cameraMediaType = AVMediaTypeVideo let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatus(forMediaType: cameraMediaType) switch cameraAuthorizationStatus { case .denied: NSLog("cameraAuthorizationStatus=denied") break case .authorized: NSLog("cameraAuthorizationStatus=authorized") break case .restricted: NSLog("cameraAuthorizationStatus=restricted") break case .notDetermined: NSLog("cameraAuthorizationStatus=notDetermined") // Prompting user for the permission to use the camera. AVCaptureDevice.requestAccess(forMediaType: cameraMediaType) { granted in DispatchQueue.main.sync { if granted { // do something } else { // do something else } } } } } 

Answer 4

Swift：使用AVFoundation

1. 将AVFoundation添加到目标 – >构build阶段 – >与库链接二进制文件。
2. 在ViewController上导入AVFoundation。
3. 在Info.plist上，添加以下内容：

4. 在视图控制器上：

@IBAction func cameraButtonClicked（sender：AnyObject）{

 let authorizationStatus = AVCaptureDevice.authorizationStatusForMediaType(AVMediaTypeVideo) print(authorizationStatus.rawValue) if AVCaptureDevice.authorizationStatusForMediaType(AVMediaTypeVideo) == AVAuthorizationStatus.Authorized{ self.openCameraAfterAccessGrantedByUser() } else { print("No Access") dispatch_async(dispatch_get_main_queue()) { [unowned self] in AVCaptureDevice.requestAccessForMediaType(AVMediaTypeVideo, completionHandler: { (granted :Bool) -> Void in if granted == true { // User granted self.openCameraAfterAccessGrantedByUser() } else { // User Rejected alertToEncourageCameraAccessWhenApplicationStarts() } }); } } //Open camera func openCameraAfterAccessGrantedByUser() { if(UIImagePickerController .isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)){ self.cameraAndGalleryPicker!.sourceType = UIImagePickerControllerSourceType.Camera cameraAndGalleryPicker?.delegate = self cameraAndGalleryPicker?.allowsEditing = false cameraAndGalleryPicker!.cameraCaptureMode = .Photo cameraAndGalleryPicker!.modalPresentationStyle = .FullScreen presentViewController(self.cameraAndGalleryPicker!, animated: true, completion: nil) } else { } } //Show Camera Unavailable Alert func alertToEncourageCameraAccessWhenApplicationStarts() { //Camera not available - Alert let cameraUnavailableAlertController = UIAlertController (title: "Camera Unavailable", message: "Please check to see if it is disconnected or in use by another application", preferredStyle: .Alert) let settingsAction = UIAlertAction(title: "Settings", style: .Destructive) { (_) -> Void in let settingsUrl = NSURL(string:UIApplicationOpenSettingsURLString) if let url = settingsUrl { dispatch_async(dispatch_get_main_queue()) { UIApplication.sharedApplication().openURL(url) } } } let cancelAction = UIAlertAction(title: "Okay", style: .Default, handler: nil) cameraUnavailableAlertController .addAction(settingsAction) cameraUnavailableAlertController .addAction(cancelAction) self.window?.rootViewController!.presentViewController(cameraUnavailableAlertController , animated: true, completion: nil) }