设置项目大标题

    if(@available(iOS 11.0,*)){

        self.navigationController.navigationBar.prefersLargeTitles = YES;

        self.navigationController.navigationBar.tintColor =[UIColor whiteColor];

        self.navigationController.navigationItem.largeTitleDisplayMode =  UINavigationItemLargeTitleDisplayModeAutomatic;

        self.navigationController.navigationBar.largeTitleTextAttributes =[NSDictionary dictionaryWithObjectsAndKeys:UIColor.whiteColor,NSForegroundColorAttributeName,nil];//改变大标题颜色

    }