Custom UINavigationBar Background

tigermain_258 0
Viewed 52940

I've been trying to set up a custom background for the whole of my NavigationBar (not just the titleView) but have been struggling.

I found this thread

http://discussions.apple.com/thread.jspa?threadID=1649012&tstart=0

But am not sure how to implement the code snippet that is given. Is the code implemented as a new class? Also where do I instatiate the UINavigationController as I have an application built with the NavigationView template so it is not done in my root controller as per the example

objective-c iphone
15 Answers

You can also override the drawLayer:inContext: method in a UINavigationBar category class. Inside the drawLayer:inContext: method, you can draw the background image you want to use.

- (void) drawLayer:(CALayer *)layer inContext:(CGContextRef)context
{
    if ([self isMemberOfClass:[UINavigationBar class]] == NO) {
        return;
    }

    UIImage *image = (self.frame.size.width > 320) ?
                        [UINavigationBar bgImageLandscape] : [UINavigationBar bgImagePortrait];
    CGContextClip(context);
    CGContextTranslateCTM(context, 0, image.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    CGContextDrawImage(context, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height), image.CGImage);
}

And as a complete demo Xcode project on customizing the appearance of UINavigationBar this and this might be helpful.

user_3195890

As Apple itself has said, it is not correct to override methods in Categories. So the best way to customize the background of UINavigarionBar is subclassing and override -(void)drawInRect: method.

@implementation AppNavigationBar
- (void)drawRect:(CGRect)rect
{
    UIImage *patternImage = [UIImage imageNamed:@"image_name.png"];
    [patternImage drawInRect:rect];
}

To use this customized UINavigationBar it should be set as navigationBar property of your UINavigationBarController. As you know this property is readonly. So what should be done is:

- (void)viewDidLoad
{
    [super viewDidLoad];

    AppNavigationBar *nav = [AppNavigationBar new];
    [self setValue:nav forKey:@"navigationBar"];
}

It works for both iOS 5 and 4.3.

user_4746330
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