当我们自定义继承UIViewController视图控制器的基类视图控制器时，会新增返回到上级的视图控制器方法，于是就要区分，返回时使用 pop 的方法，还是使用dismiss 的方法了。

方法1

[html] view plain copy 在CODE上查看代码片派生到我的代码片

- (void)backPreviousController

{

if (self.presentingViewController)

{

[self dismissViewControllerAnimated:YES completion:nil];

}

else

{

[self.navigationController popViewControllerAnimated:YES];

}

}

方法2

[objc] view plain copy 在CODE上查看代码片派生到我的代码片

- (void)backPreviousController

{

if (self.navigationController.topViewController == self)

{

[self.navigationController popViewControllerAnimated:YES];

}

else

{

[self dismissViewControllerAnimated:YES completion:nil];

}

}

方法3

[objc] view plain copy 在CODE上查看代码片派生到我的代码片

- (void)backPreviousController

{

if ([self.navigationController.viewControllers.firstObject isEqual:self])

{

[self dismissViewControllerAnimated:YES completion:nil];

}

else

{

[self.navigationController popViewControllerAnimated:YES];

}

}

[html] view plain copy 在CODE上查看代码片派生到我的代码片

- (void)backPreviousController

{

if ([self.navigationController.viewControllers indexOfObject:self] == 0)

{

[self dismissViewControllerAnimated:YES completion:nil];

}

else

{

[self.navigationController popViewControllerAnimated:YES];

}

}