无法更改cameraFlashMode for UIImagePickerController iphone 4自定义cameraOverlayView

Question

问题：为什么imagePickerController.cameraFlashMode总是在iphone 4上返回0并使用iphone 5返回正确的值？

我初始化我的UIImagePickerController并将cameraFlashMode设置为UIImagePickerControllerCameraFlashModeOn：

imagePickerController = [[UIImagePickerController alloc] init];
imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
imagePickerController.mediaTypes = [NSArray arrayWithObject:@"public.image"];
imagePickerController.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
imagePickerController.showsCameraControls = NO;
imagePickerController.cameraFlashMode = UIImagePickerControllerCameraFlashModeOn;
[rest of overlay creation...]

然后按下我的自定义叠加层的flash按钮时，会触发此方法：

正如您在下面的屏幕截图中所看到的，在变量视图中，cameraFlashMode的值是正确的＆＃39;但是使用NSLog和imagePickerController.cameraFlashMode

返回0

NSLog(@"current cameraFlashMode=%d", imagePickerController.cameraFlashMode); //returns 0 (iphone 4)

然而，在iphone 5上，可以毫无问题地访问该值：

NSLog(@"current cameraFlashMode=%d", imagePickerController.cameraFlashMode); //returns 1 (iphone 5)