Difference between viewdidappear and viewwillappear in swift

- The viewWillAppear method is called when the presentation of the view in the view hierarchy is about to start.

- The viewDidAppear method is called when the presentation of the view is done, notably when any and all associated animation has finished.

 

stackoverflow.com/questions/5630649/what-is-the-difference-between-viewwillappear-and-viewdidappear#:~:text=The%20viewWillAppear%20method%20is%20called%20when%20the%20presentation%20of%20the,hierarchy%20is%20about%20to%20start.&text=The%20viewDidAppear%20method%20is%20called%20when%20the%20presentation%20of%20the,all%20associated%20animation%20has%20finished.

What is the difference between -viewWillAppear: and -viewDidAppear:?