最近做项目遇到一种需求: 需要将navigationBar设置为透明。效果如下：
我的做法是先隐藏原来的navigation:
self.navigationController.navigationBarHidden = YES;
然后添加一个navigationBar：
//添加一个UINavigationBar
CGRect screenRect = [[UIScreen mainScreen] bounds];
imageNavigationBar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, screenRect.size.width, 64)];
[self.view addSubview: imageNavigationBar];
//往imageNavigationBar上设置背景图
UIImage *barImage = [UIImage imageNamed:@"bg_home_nav"];
UIImage *scaleBarImage = [[UIImage alloc] init];
scaleBarImage = [scaleBarImage image:barImage byScalingToSize:CGSizeMake(SCREEN_WIDTH, 64)];
[imageNavigationBar setBackgroundImage:scaleBarImage forBarMetrics:UIBarMetricsDefault];
imageNavigationBar.shadowImage = [UIImage new];
imageNavigationBar.translucent = NO;
gotta
