添加有背景图片的按钮

按钮实现有背景图片，没有title，在点击时有相应，将按钮添加到导航条中，导航条如下：

-(void)viewDidLoad{
[super viewDidLoad];
    [self.navigationBar setFrame:CGRectMake(0,0,320,50)];
    self.navigationBar.tintColor=[UIColor whiteColor];
}

现在显示出白色的导航条，接下来怎么添加带图片的按钮？
谢谢

-(void)viewDidLoad{
[super viewDidLoad];
    [self.navigationBar setFrame:CGRectMake(0,0,320,50)];
    self.navigationBar.tintColor=[UIColor whiteColor];

   UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"yourImageName"]
                         style:UIBarButtonItemStyleBordered
                        target:self action:@selector(yourButtonPressMethodName:)];   
    self.navigationItem.leftBarButtonItem = item;//use rightBarButtonItem if you want to add button on right dife
}

用自定义视图设置UIBarButtonItem :

UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[btn setFrame:CGRectMake(0.0, 0.0, 75.0, 40.0)];
[btn setImage:[UIImage imageNamed:@"anyImage.png"] forState:UIControlStateNormal];
[btn addTarget:self action:@selector(yourAction) forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *barbutton = [[UIBarButtonItem alloc]initWithCustomView:btn];
self.navigationItem.leftBarButtonItem = barbutton;

把系统的导航条隐藏了，自己写一个view吧。系统的可定制性太差了，往往不符合要求。