定制navgation上的按钮

代码示例：

UIImage *image  = [UIImageimageNamed:@"radio_back.png"];

        UIButton* button= [[UIButtonalloc] initWithFrame:CGRectMake(0,0, image.size.width,image.size.height)];

        button.adjustsImageWhenHighlighted =YES; // 按按钮时，显示按钮的变化

        [button setBackgroundImage:imageforState:UIControlStateNormal];

        [button addTarget:selfaction:@selector(onBack:)forControlEvents:UIControlEventTouchUpInside];

        

UIBarButtonItem* ButtonItem = [[UIBarButtonItemalloc] initWithCustomView:button] ;

self.navigationItem.leftBarButtonItem = ButtonItem ;

[ButtonItem release] ;

        [button release];

UIBarButtonItem虽然有initWithImage,但只是设置前景图，背景框仍在。setBackgroundImage有测试过，但会崩溃就没有深究。