iPhone - NavigationBar Custom Background [duplicat

问题:

Possible Duplicate:
How to add background image on iphone Navigation bar?

I am looking for a way to have a custom navigation bar and need to have a custom navigation bar background to achieve this. I was looking around for how to do this, but could not find a solution. If anyone has the solution, help is much appreciated.

回答1:

You can just add a subview (a UIImageView) to the navaigationBar, which is just a UIView subclass.

UINavigationBar nb = [[UINavigationBar alloc]init];
[nb addSubview: foo];
[nb release];

Here's a forum post that describes how to wrap this up into a category: http://discussions.apple.com/thread.jspa?threadID=1649012&tstart=0

回答2:

Since iOS5, you can easily set a custom background, with the method setBackgroundImage:forBarMetrics: But you must check if the user's phone has the right OS.

if ([self.navigationController.navigationBar respondsToSelector:@selector(setBackgroundImage:forBarMetrics:)])
{
    [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"texture.png"]
                                                  forBarMetrics:UIBarMetricsDefault];
}

This is a nicer solution, cause it's in the doc.

回答3:

(supplemental to Andrew Johnson's response)

The linked Apple.com post includes 3 or 4 different solutions, most of which only "half" work. I think the most elegant/effective of them is this one:

@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

HOWEVER ... it's not good-practice ObjC to od that as a category (should be an override), and it has some problems of its own.

So, a more general and powerful solution is here:

http://samsoff.es/posts/customize-uikit-with-method-swizzling

回答4:

Copy this into viewDidLoad. It will check for iOS 5 and use the preferred method, otherwise it will add a subview to the navBar for iOS versions < 5.0. This will work provided that your custom background image has no transparencies.

float version = [[[UIDevice currentDevice] systemVersion] floatValue];
NSLog(@"%f",version);
UIImage *backgroundImage = [UIImage imageNamed:@"myBackgroundImage.png"];
if (version >= 5.0) {
    [self.navigationController.navigationBar setBackgroundImage:backgroundImage forBarMetrics:UIBarMetricsDefault];
}
else
{
    [self.navigationController.navigationBar insertSubview:[[[UIImageView alloc] initWithImage:backgroundImage] autorelease] atIndex:1];
}