cameraOverlayView不适用

Question

当我尝试将cameraOverlayView应用到UIImagePickerController时，它不会出现。我已经阅读了一些关于如何应用这一点的文档，我的代码看起来都是正确的。如果有人能解释为什么我的覆盖还没有开始的话，我真的会理解的。

//Start the camera up

UIImagePickerController *imageViewPickerController = [[UIImagePickerController alloc] init];

//Hide default UI elements

imageViewPickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
imageViewPickerController.showsCameraControls = NO;
imageViewPickerController.navigationBarHidden = YES;
imageViewPickerController.toolbarHidden = YES;

//Start the button overlay

UIView *btnView = [[UIView alloc] initWithFrame:imageViewPickerController.view.bounds];
btnView.backgroundColor = [UIColor whiteColor];
btnView.alpha = 0.3;
btnView.clipsToBounds = YES;

//Add a button to the overlay

UIButton *snapButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 1024, 1024)];
snapButton.backgroundColor = [UIColor blackColor];
[btnView addSubview:snapButton];

//Overlay button view

imageViewPickerController.cameraOverlayView = btnView;

//Fix for iPhone 5 and make fullscreen

CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, -55.0);
CGAffineTransform scale = CGAffineTransformMakeScale(1.333333, 1.333333);
CGAffineTransform rotate = CGAffineTransformMakeRotation(DEGREES_RADIANS(180));
CGAffineTransform transform = CGAffineTransformConcat(translate, scale);
transform = CGAffineTransformConcat(transform, rotate);
imageViewPickerController.cameraViewTransform = transform;

//Let's present it all

[self presentViewController:imageViewPickerController
                   animated:NO
                 completion:NULL];

解决办法：

我找到了解决方案:它既合并了Visput的建议，又合并了fguchelaar的，然后我删除了btnView.alpha = 0.3，用btnView.opaque = NO;替换了它，这就成功了。混乱的颜色，现在我的覆盖是完美的工作。

Answer 1

覆盖视图的框架大小为零：

UIView *btnView = [[UIView alloc] initWithFrame:CGRectZero];

像这样改变它，你就会看到它：

UIView *btnView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 1024];

更新：

还启用clipsToBounds标志：btnView.clipsToBounds = YES;