问题
(iOS 7.0.3, Xcode 5.0.1)
I have a second UIWindow in my app used to display a custom magnifier above the status bar. However, once I set the rootViewController of this window (for interface rotation & some other stuff), the main window goes black during the interface rotation animation.
To reproduce: create single view iOS application and add the following to the main UIViewController.
// To @interface:
@property (nonatomic, strong) UIWindow *secondWindow;
// In viewDidLoad:
self.secondWindow = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
self.secondWindow.rootViewController = [[UIViewController alloc] initWithNibName:nil bundle:nil];
self.secondWindow.hidden = NO;
Any help appreciated.
回答1:
I will add another answer, because I have found a workaround that actually works. Set the window's background color, as well as the view controller's view's background color to a color with an alpha of 0. Do not use clearColor, but rather use something like greenColor] colorWithAlphaComponent:0.0]; It works.
回答2:
According to an Apple engineer on the dev forums, this is expected due to the window adding a black background to avoid things behind it to be seen (i.e. behind the main window normally). I opened and issue with the Apple bug tracker, #15398141.
Nevertheless, I worked around the issue by hiding the window in willRotateToInterfaceOrientation:duration: and unhiding it in didRotateFromInterfaceOrientation:, which luckily is not a big deal in this case.
回答3:
This is a known issue, and there are many radars open for it. Best solution so far for me is to add a view as a subview to the window, and manage rotation yourself. This works well.
回答4:
Make window.opaque = No whose default value is YES. In my case it solved the problem.
来源：https://stackoverflow.com/questions/19782944/blacked-out-interface-rotation-when-using-second-uiwindow-with-rootviewcontrolle