Changing the UINavigationBar background image

Considering all iOS versions, this seems to be accomplishing both Custom background image and Custom size of UINavigationBar:

@interface CustomNavigationBar : UINavigationBar
@end

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

    //for iOS5
    [self setBackgroundImage:[UIImage imageNamed: @"navigationBar"] forBarMetrics:UIBarMetricsDefault];
}

//for custom size of the UINavigationBar
- (CGSize)sizeThatFits:(CGSize)size {
    CGSize newSize = CGSizeMake(320,31);
    return newSize;
}

@end

I use such codes in a common place like a Utilities file.

Hope this helps.

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)

Just try with this code.. In your implmentation (.m) file.

#import "RootViewController.h"

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

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;

    self.title=@"You are Done.";
}

This has worked in excellent way for me.

Above Code Worked for only IOS 4. if you use the IOS 5 then use.....

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