关于 导航条、状态栏的相关设置
// 导航条 变透明,去掉黑线
[[UINavigationBar appearance] setBackgroundImage:[[UIImage alloc] init] forBarPosition:UIBarPositionAny barMetrics:UIBarMetricsDefault];
[[UINavigationBar appearance] setShadowImage:[[UIImage alloc] init]];
//状态栏 字颜色变白 + info 设置属性View controller-based status bar appearance设为NO
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];