navigationBar设置背景颜色现阶段我有四种方法

方法1、
UIImage *topImage = [UIImage imageNamed:@"Navigation-Bar_backgroud_44@2x"];
    [[UINavigationBar appearance] setBackgroundImage:topImage forBarMetrics:UIBarMetricsDefault];

方法二
    self.navigationController.navigationBar.barTintColor = [UIColor redColor];

方法三
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@""] forBarMetrics:UIBarMetricsDefault];

方法四
    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 320, 44)];
    [self.navigationItem setTitleView:label];