Viewcontroller life cycle

1. Object creation (instantiation), two ways to create it: Alloc/init, Initwithnibname

2.awakeFromNib, when using IB, that is instantiated using Initwithnibname to call this method

3. Set output (outlet), Iboutlet attribute to view, call its Get/set method

4.viewDidLoad, will only be called once

5. When the view geometry content on the screen is determined, viewwill/didlayoutsubviews,e.g draws the shape of the graphic, the screen rotates

6.viewwill/didappear, called when the Viewcontroller view is coming/has occurred

7. (possible) The viewwill/didlayoutsubviews,e.g screen rotates when there is a change in the visible content on the screen, the animation

8.viewwill/diddissapear, called when the Viewcontroller view is about/has disappeared

9. (possible) When system memory is low, didreceivememorywarning

Viewcontroller life cycle