在iPhone上同时打开闪光灯和前置摄像头

Question

我需要使用前置摄像头，并在iPhone中打开背光LED。我该怎么做？我可以使用以下代码打开前置摄像头：

- (void) turnCameraOn {
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
    imagePicker.cameraDevice = UIImagePickerControllerCameraDeviceFront;
    imagePicker.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
    imagePicker.showsCameraControls = YES;
    [self presentViewController:imagePicker animated:YES completion:nil];
} else {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Camera unavaliable"
                                                    message:@"Unable to find camera on your device."
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil, nil];
    [alert show];
    alert = nil;
}
}

我可以用这个代码打开led

- (void) turnTorchOn: (bool) on {
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if ([device hasTorch] && [device hasFlash]){
        [device lockForConfiguration:nil];
        if (on) {
            [device setTorchMode:AVCaptureTorchModeOn];
            [device setFlashMode:AVCaptureFlashModeOn];
        } else {
            [device setTorchMode:AVCaptureTorchModeOff];
            [device setFlashMode:AVCaptureFlashModeOff];
        }
        [device unlockForConfiguration];
    }
}
}

但当我打开应用程序，前置摄像头出现时，led熄灭了。我需要两个人同时工作。

感谢

Answer 1

这在具有当前API集的iOS上是不允许的。你可以通过苹果自己的相机应用程序来理解这一点。

甚至当你切换到使用前置摄像头时，他们也会关闭手电筒，并且在该模式下不会显示手电筒开关。

Answer 2

从文档中检查UIImagePickerController的isFlashAvailableForCameraDevice属性，以检查是否允许使用UIImagePickerControllerCameraDeviceFront属性的闪光灯。