一 . UINavigationBar
1.获取 UINavigationBar 对象: [UINavigationBar appearance] ,可以通过该方法对全部 navigation 进行设置
2.设置导航栏背景图片:[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"name"] forBarMetrics:UIBarMetricsDefault];
3.设置标题字体:[UINavigationBar appearance].titleTextAttributes = @{NSForegroundColorAttributeName:[UIColor whiteColor]};
二 . UIBarButtonItem
1.获取 UIBarButtonItem 对象: [UIBarButtonItem appearance] 可以通过该方法实现对 barButtonItem (即导航栏按钮)样式,显示字体进行设置 (同一 navigation 下全部)
2.设置按钮的颜色,大小 : [[UIBarButtonItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor whiteColor],NSFontAttributeName:[UIFont systemFontOfSize:13]} forState:UIControlStateNormal];
3.设置导航栏渐变色(返回箭头白色) : [UIBarButtonItem appearance].tintColor = [UIColor whiteColor];
