自定义NavigationBar

 [self.navigationController.navigationBarsetHidden:YES];

    CGRect screenRect = [[UIScreen mainScreen] bounds];

    UINavigationBar *navigationBar = [[UINavigationBar alloc]initWithFrame:CGRectMake(0, 0, screenRect.size.width, 64)];

    navigationBar.tintColor = [UIColor greenColor];

    navigationBar.alpha=0.3;

    //创建UINavigationItem

    UINavigationItem *navigationbarTitle = [[UINavigationItem alloc] initWithTitle:@"城市列表"];

    [navigationBar pushNavigationItem:navigationbarTitle animated:YES];

    navigationBar.backgroundColor =[UIColor clearColor];

    

    //创建UIBarButton

    UIBarButtonItem *itemL = [[UIBarButtonItemalloc]initWithBarButtonSystemItem:UIBarButtonSystemItemReplytarget:selfaction:@selector(navigationBackButton:)];

    UIBarButtonItem *itemR = [[UIBarButtonItemalloc]initWithBarButtonSystemItem:UIBarButtonSystemItemCameratarget:selfaction:@selector(navigationBackButton:)];

    

    //设置BarButton

    navigationbarTitle.leftBarButtonItem = itemL;

    navigationbarTitle.rightBarButtonItem = itemR;

    [navigationBar setItems:[NSArray arrayWithObject:navigationbarTitle]];

    [self.imageView addSubview:navigationBar];