Ios – Changing the UINavigationBar background image

iosiphoneuinavigationbaruinavigationcontroller

I've been trying to change the background image of the UINavigationBar of my application. I tried several ways. First I added to my AppDelegate class the following code:

@implementation UINavigationBar (CustomImage)
    - (void)drawRect:(CGRect)rect {
    UIImage *image = [UIImage imageNamed: @"navigationbar.png"];
    [image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
}
@end

But it wasn't working. My next try was to write a CustomizedNavigationBar Class which is overriding the drawRect method. It looked like that:

CustomizedNavigationBar.h

#import <UIKit/UIKit.h>

@interface CustomizedNavigationBar : UINavigationBar

@end

CustomizedNavigationBar.m

#import "CustomizedNavigationBar.h"

@implementation CustomizedNavigationBar

- (void) drawRect:(CGRect)rect {
    UIImage *image = [UIImage imageNamed: @"navigationbar.png"];
    [image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];

    NSLog(@"I got called!!!!!");
}

@end

In my .xib file where the NavigationBar is defined I changed the class to the new CustomizedNavigationBar. But still it is not working..

As another test I downloaded an example project where the background image should be changed. But even with that sample code it was not working.

What am I doing wrong? I am using IOS 5. Any suggestions or other ways I could define a background image?

Thanks for your answers!

Best Answer

Starting in iOS 5 you should use the -setBackgroundImage:forBarMetrics: method:

[myNavbar setBackgroundImage:[UIImage imageNamed: @"UINavigationBarBackground.png"] 
               forBarMetrics:UIBarMetricsDefault];

And in Swift 4:

navigationBar.setBackgroundImage(UIImage(named: "UINavigationBarBackground.png"),
               for: .default)

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R – UINavigationBar background image via drawRect – issue with prompt animation

So very "hacky", but this is the closest I can get it to do what I want...

Basically when method swizzling, simply letting the image stretch wasn't working well for me because I also had rounded corners. So instead I made the corners a separate transparent img and add it as a subview so they wouldn't get affected by the stretch animation.

So my category now looks like this..

#import "UINavigationBar+custom.h"

#define cornersTag 1

@implementation UINavigationBar (UINavigationBarCategory)

-(void)setCornersIfNeeded{
 UIImageView *corners = (UIImageView*)[self viewWithTag:cornersTag];
 if(!corners){
  UIImage *img = [[UIImage imageNamed:@"navbar_corners.png"] stretchableImageWithLeftCapWidth:10 topCapHeight:0];
  corners = [[[UIImageView alloc] initWithImage:img] autorelease];
  corners.frame = CGRectMake(0, 0, self.frame.size.width, img.size.height);
  corners.tag = cornersTag;
  [self addSubview:corners];
 }
}

- (void)customDrawRect:( CGRect )rect{
 [self customDrawRect:rect];
 [[UIImage imageNamed:@"navbar.png"] drawInRect:rect]; 
 [self setCornersIfNeeded];
}

@end

for more on method swizzling... http://www.cocoadev.com/index.pl?MethodSwizzling and Method Swizzle on iPhone device

Best Answer

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