viewWillAppear is called on UIViewController when a view is about to be shown on screen. Is it possible to get similar callback on UIView?
当视图即将在屏幕上显示时，在UIViewController上调用viewWillAppear。是否有可能在UIView上获得类似的回调？
2 个解决方案
#1
41
How about the following from the UIView reference
如何从UIView引用中得到以下内容
willMoveToSuperview:, didMoveToSuperview - Implement these methods as needed to track the movement of the current view in your view hierarchy.
willMoveToSuperview：，didMoveToSuperview - 根据需要实现这些方法，以跟踪视图层次结构中当前视图的移动。
this will at least tell you when it is added to a view hierarchy but there is no guarantee that the view hierarchy is presented/viewable.
这至少会告诉您何时将其添加到视图层次结构中，但不能保证视图层次结构是可呈现/可查看的。
#2
6
No, but you can forward that notification to the desired view from your view controller.
不，但您可以从视图控制器将该通知转发到所需的视图。
#1
41
How about the following from the UIView reference
如何从UIView引用中得到以下内容
willMoveToSuperview:, didMoveToSuperview - Implement these methods as needed to track the movement of the current view in your view hierarchy.
willMoveToSuperview：，didMoveToSuperview - 根据需要实现这些方法，以跟踪视图层次结构中当前视图的移动。
this will at least tell you when it is added to a view hierarchy but there is no guarantee that the view hierarchy is presented/viewable.
这至少会告诉您何时将其添加到视图层次结构中，但不能保证视图层次结构是可呈现/可查看的。
#2
6
No, but you can forward that notification to the desired view from your view controller.
不，但您可以从视图控制器将该通知转发到所需的视图。