设置返回按钮
 UIBarButtonItem *bar = [[UIBarButtonItem alloc] initWithTitle:@"返回" style:0 target:nil action:nil];
 [self.navigationItem setBackBarButtonItem:bar];
 
 设置navititle颜色
 self.navigationController.navigationBar.tintColor = [UIColor whiteColor];

 显示隐藏tabbar
 - (void)viewWillAppear:(BOOL)animated{
 [super viewWillAppear:animated];
 self.tabBarController.tabBar.hidden = YES;
 }
 - (void)viewWillDisappear:(BOOL)animated{
 [super viewWillDisappear:animated];
 self.tabBarController.tabBar.hidden = NO;
 }
 
 非半透明，且隐藏黑线
 [[UINavigationBar appearance] setTranslucent:NO];
 self.navigationController.navigationBar.subviews[0].subviews[0].hidden = YES;

添加右侧按钮
UIBarButtonItem *anotherButton = [[UIBarButtonItem alloc] initWithTitle:@"提交" style:UIBarButtonItemStylePlain target:self action:@selector(feedbackAction)];
    self.navigationItem.rightBarButtonItem = anotherButton;