Viewwillappear: viewdidappear: viewwilldisappear: viewdiddisappear: loadview

Viewwillappear:
Called when the view is about to made visible. Default does nothing

Called when the view is about to be visible. No operations are performed by default.

viewdidappear:
called when the view has been fully transitioned onto the screen. default does nothing

Called when the view has been fully transitioned to the screen

viewwilldisappear:
called when the view is dismissed, covered or otherwise hidden. default does nothing

A view is called when it is dequeued, overwritten, or hidden in other ways. No operations are performed by default.

Viewdiddisappear:
Called after the view was dismissed, covered or otherwise hidden. Default does nothing
A view is called after it is disband and overwritten or hidden in other ways. No operations are performed by default.

Loadview;
This is where subclasses shocould create their custom view hierarchy if they aren't using a nib. shocould never be called directly.

This is when they are not using the nib view page, the subclass will create its own custom view layer. It must not be called directly.

Viewdidload;
Called after the view has been loaded. For view controllers created in code, this is after-loadview. For view controllers Unarchived from
NIB, this is after the view is set.
Called after the view is loaded.CodeThe created view loader will be called after the loadview method. If it is output from the nib view page, it will be called after the view is set