- (void)viewDidLoad {
    [self setNavgation]; //需要在
}


-(void) setNavgation{
    self.navigationItem.hidesBackButton = YES;//可以隐藏原有的导航栏返回按钮
    //设置的按钮会显示在导航栏左边，返回按钮的位置
    UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"activity_back.png"] style:UIBarButtonItemStylePlain target:self action:@selector(backViewcontroller)];
    self.navigationItem.leftBarButtonItem = barButtonItem;
    UINavigationBar *bar = [UINavigationBar appearance];

    //设置显示的颜色
    bar.barTintColor = [UIColor clearColor];
    //设置字体颜色
    bar.tintColor = [UIColor whiteColor];
    [bar setTitleTextAttributes:@{NSForegroundColorAttributeName : [UIColor whiteColor]}];

}