- (void)viewWillAppear:(BOOL)animated {
//设置导航栏背景图片为一个空的image，这样就透明了
[self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
//去掉透明后导航栏下边的黑边
[self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];
}
- (void)viewWillDisappear:(BOOL)animated {
[self.navigationController.navigationBar setBackgroundImage:nil forBarMetrics:UIBarMetricsDefault];
[self.navigationController.navigationBar setShadowImage:nil];
}
只会消失当前vc的导航条线条，push的下个页面没有影响
