Customised UINavigationBar background in iOS 4 and 5

Posted on November 2, 2011

1


Recently I came across the situation that I needed to support a custom background for a UINavigationBar in an app that had to work for both iOS 4 and iOS 5. After some Googling I came up with this approach.

First the easy one, iOS 5;

if ([[UINavigationBar class] respondsToSelector:@selector(appearance)]) {
    [self.navigationController.navigationBar setBackgroundImage:navigationBackgroundImage forBarMetrics:UIBarMetricsDefault];
}

Note the test on the navigation bar class to check if it supports the UI proxy extensions. This must be done in iOS 4 otherwise a crash will result.

Now for iOS 4 we have to create a category, fortunately this is very simple;

@implementation UINavigationBar (CustomBackground)

- (void)drawRect:(CGRect)rect
{
    UIImage *navBackgroundImage = [[UIImage imageNamed:@"navigation-background"] stretchableImageWithLeftCapWidth:0.0 topCapHeight:0.0];
    [navBackgroundImage drawInRect:rect];
}

@end

The drawRect: method is not called in iOS 5 so it is safe to leave this category in your app. Just as a small side note, Apple has deprecated strechableImageLeftCapWidth:topCapHeight: in iOS 5 in favour of resizableImageWithCapInsets:.

Advertisements