iOS 隐藏/显示导航栏

一、隐藏导航栏

[self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
[self.navigationController.navigationBar setShadowImage:[UIImage new]];

二、显示导航栏

[self.navigationController.navigationBar setBackgroundImage:nil forBarMetrics:UIBarMetricsDefault];
[self.navigationController.navigationBar setShadowImage:nil];