ios - [viewController.view removeFromSuperView] 之间的差异；和 [viewController removeFromParentViewController];？

Question

有什么区别

[viewController.view removeFromSuperView]; 

和

[viewController removeFromParentViewController]; ?

我只是想从UIScrollView中移除一个子视图，当然代码应该是这样的[viewController.view removeFromSuperView];

但是当我尝试时[viewController removeFromParentViewController];，它似乎也很实用。诡异的！