隐藏导航栏
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[self.navigationController setNavigationBarHidden:YES];
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
}
显示导航栏
-(void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[self.navigationController setNavigationBarHidden:NO];
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault];
}