如何检测相机是否受用户限制

Question

我正在做一个带有启动相机按钮的 ios 应用程序。

如果设备有可用的摄像头，我想启用/禁用按钮。

我想检测设备是否有摄像头，以及设备是否有摄像头但受到限制（使用this），因此您无法使用它。

如何检测这两个选项？

谢谢

Answer 1

要检查应用程序中的相机权限状态，请使用以下 sn-p。

@import AVFoundation;

if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
 {
  AVAuthorizationStatus status = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];

  if(status == AVAuthorizationStatusAuthorized) {
    // authorized
  } else if(status == AVAuthorizationStatusDenied){
    // denied
  } else if(status == AVAuthorizationStatusRestricted){
    // restricted
  } else if(status == AVAuthorizationStatusNotDetermined){
      // not determined
      [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
          if(granted){
            NSLog(@"Granted access");
          } else {
            NSLog(@"Not granted access");
          }
      }];
   }
}

Answer 2

SWIFT 3

要决定是否应该启用（或隐藏）相机按钮，您应该检查：

    if UIImagePickerController.isSourceTypeAvailable(.Camera){ }

然后我会检查用户是否允许访问相机，正如苹果在他们的 PhotoPicker 示例 (PhotoPicker example Objective-C) 中所建议的那样：

*请注意您必须导入 AVFoundation

let authStatus = AVCaptureDevice.authorizationStatus(forMediaType: AVMediaTypeVideo)

if authStatus == AVAuthorizationStatus.denied {
    // Denied access to camera
    // Explain that we need camera access and how to change it.
    let dialog = UIAlertController(title: "Unable to access the Camera", message: "To enable access, go to Settings > Privacy > Camera and turn on Camera access for this app.", preferredStyle: UIAlertControllerStyle.alert)

    let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil)

    dialog.addAction(okAction)
    self.present(dialog, animated:true, completion:nil)

} else if authStatus == AVAuthorizationStatus.notDetermined {     // The user has not yet been presented with the option to grant access to the camera hardware.
    // Ask for it.
    AVCaptureDevice.requestAccess(forMediaType: AVMediaTypeVideo, completionHandler: { (grantd) in
    // If access was denied, we do not set the setup error message since access was just denied.
       if grantd {
       // Allowed access to camera, go ahead and present the UIImagePickerController.
            self.showImagePickerForSourceType(sourceType: UIImagePickerControllerSourceType.camera)
        }
    })
} else {

    // Allowed access to camera, go ahead and present the UIImagePickerController.
    self.showImagePickerForSourceType(sourceType: UIImagePickerControllerSourceType.camera)

}

func showImagePickerForSourceType(sourceType: UIImagePickerControllerSourceType) {

    let myPickerController = UIImagePickerController()
    myPickerController.delegate = self;
    myPickerController.sourceType = sourceType  
    self.present(myPickerController, animated: true, completion: nil)
}

Answer 3

如其他地方所述，检查AVAuthorizationStatus 实际上不会告诉您它是否受到限制，尽管枚举中存在“限制”值。 相反，我发现检查源是否启用很有帮助：

BOOL isCameraAvailable = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];

如果isCameraAvailable 是NO，那么用户很可能在限制中禁用了相机。见Detect existence of camera in iPhone app?

Answer 4

检查相机是否受限AVAuthorizationStatus 是不够的。如文档中所述：

此状态通常不可见 - 用于发现设备的 AVCaptureDevice 类方法不会返回用户被限制访问的设备。

因此，为了正确检查，您需要创建一些捕获设备，例如，就像我所做的那样：

AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if (authStatus == AVAuthorizationStatusAuthorized) {
    BOOL atLeastOne = NO;
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if (device) {
            atLeastOne = YES;
        }
    }
    if (!atLeastOne) {
        authStatus = AVAuthorizationStatusRestricted;
    }
}

Answer 5

用户第一次尝试在 ios 6 上使用相机时，系统会自动要求他/她获得许可。您不必添加额外的代码（在授权状态为 ALAuthorizationStatusNotDetermined 之前）。

所以如果用户第一次拒绝你就不能再问了。

您可以使用 ALAssetsLibrary 进行检查。 检查此解决方案的答案： ask-permission-to-access-camera

希望对你有帮助。