setBackButtonBackgroundImage Weard Behaviour on iOS5.1

Question

I have two différent behaviour on ios5.1 and ios6.0 with

[[UIBarButtonItem appearance] setBackButtonBackgroundImage:offBackButton forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];

On iOS 6.0

On iOS 5.1 ???

Is there something I'm not doing well ?

Answer 1

You need to specify a stretchable UIImage with UIEdgeInsets as below:

UIImage *normalStateImage = [[UIImage imageNamed:@"image"] resizableImageWithCapInsets:UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0)];
UIImage *pressedStateImage = [[UIImage imageNamed:@"image-pressed"] resizableImageWithCapInsets:UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0)];

[[UIBarButtonItem appearance] setBackButtonBackgroundImage:normalStateImage forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UIBarButtonItem appearance] setBackButtonBackgroundImage:pressedStateImage forState:UIControlStateHighlighted barMetrics:UIBarMetricsDefault];

iOS 6.x is clever enough to determine the image sizes and stretch according to it.