前言

iOS推出与退出界面有两种方式——push与present，接下来笔者分别介绍这两种方式

一、push方法

    SecondViewController *second = [[SecondViewController alloc] init];
    [self.navigationController pushViewController:second animated:YES];

二、pop方法

	//返回上一级
	[self.navigationController popViewControllerAnimated:YES];

	//返回根视图
	[self.navigationController popToRootViewControllerAnimated:YES];

	//返回指定级数 （objectAtIndex:参数为想要返回的级数）
	[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:0]  animated:YES];

三、present方法

    SecondViewController *second = [[SecondViewController alloc] init];
    [self presentViewController:second animated:YES completion:nil];

四、dismiss方法

    [self dismissViewControllerAnimated:YES completion:nil];

五、dismiss多级的方法

presentedViewController和presentingViewController是UIViewController里面的两个属性
PresentedViewController 与 PresentingViewController区别

presentedViewController：The view controller that was presented by this
view controller or its nearest ancestor. 由这个视图控制器或它最近的祖先呈现的视图控制器
presentingViewController：The view controller that presented this view
controller (or its farthest ancestor.) 呈现此视图控制器(或其最远祖先)的视图控制器。

假设从A控制器通过present的方式跳转到了B控制器，那么 A.presentedViewController 就是B控制器；
B.presentingViewController 就是A控制器；

举例

创建四个页面ABCD，例如我们想从D->A，我们可以用如下方法：

    UIViewController *rootVC = self.presentingViewController;
     while  (rootVC. presentingViewController ) {
              rootVC = rootVC.presentingViewController ;
             }
    [rootVC dismissViewControllerAnimated:YES completion:nil];

例如我们想从D->B，我们可以使用presenting来跳转页面

    [self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];

如下代码也可以实现D->B

    UIViewController *rootVC =  self.presentingViewController;
    while (![rootVC isKindOfClass:[SecondViewController class]])  {
        rootVC = rootVC.presentingViewController;
    }
    [rootVC dismissViewControllerAnimated:YES completion:nil];

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