/**

 导航控制器掌握:

 1.创建导航控制器

 UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:self.viewController];

 2.zhan (zhan 中所有的子控制器)

 self.navigationController.viewControllers;

 3.将控制器压入zhan 中

     [self.navigationController pushViewController:second animated:YES];

 4.将控制器从zhan 中弹出

 1>将zhan 顶控制器弹了

 5.导航栏显示的内容

 //弹回zhan顶

 //[self.navigationController popViewControllerAnimated:YES];

 //回到 底控制器(根控制器)

 //弹回zhan 底

 [self.navigationController popToRootViewControllerAnimated:YES];

 //回到哪 人控制器

 //[self.navigationController popToViewController:animated:YES];

 5.导航栏显示的内容

 //zhan 顶控制器的navigationItem属性

 self.navigationItem.title = @"你好世界";

 self.navigationItem.leftBarButtonItem =[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemCamera target:nil action:nil];

 //设置下一个界面的返回按钮

 self.navigationItem.backBarButtonItem =[[UIBarButtonItem alloc] initWithTitle:@"返回" style:UIBarButtonItemStylePlain target:nil action:nil];

 /zhan 顶控制器的navigationItem属性决定了导航栏显示的东西@

 //导航栏左边的返回键,是由上一个键决定的

 //self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemCompose target:nil action:nil];

 self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"设置" style:UIBarButtonItemStyleDone target:self action:@selector(clickSetting)];

 // Do any additional setup after loading the view from its nib.

 6.//zhan 顶控制器

 self.navigationController.topViewController;

 */