问题
I created a new test iOS5 project in Xcode 4.2 Build 4D199 and tried to set the appearance of the UINavigationBar as described above, but nothing happens.
The code I tried in the viewDidLoad:
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"navbar-iphone.png"] forBarMetrics:UIBarMetricsDefault];
The only way I can get it to work is to set the appearance on the instance of the UINavigationBar. Like:
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"navbar-iphone.png"] forBarMetrics:UIBarMetricsDefault];
What is going on? Has anyone else had this issue?
回答1:
viewDidLoad is the wrong place to be messing with the appearance proxy of a navigation controller's navigation bar. Do this sort of thing before the navigation controller is even created. In your app delegate's applicationDidFinishLaunching is a good place.
回答2:
Did you double-check if that Imagefile does exist?
回答3:
You will need to provide forBarMetrics: for this to work.
来源：https://stackoverflow.com/questions/7855365/ios-5-uinavigationbar-appearance-setbackgroundimage-does-not-do-work