How to crawl back button navigation event?

I have a need to jump from view1 view2, then press after returning from view2 view1 display in how to do something,
In view1 with viewdidappear and viewwillappear not successful, and now really no solution! Online search did not find out a lot of information!
Reply:
A notice
In view2's viewWillDisappear or viewDidDisappear li pushNotification

Two agents
In view2's viewWillDisappear or viewDidDisappear li [delegate xxx];
Reply:
The notification bar. . .

NSNotification

In view1 add a variable for receiving notification of the state, through the variable in viewWillAppear run custom methods
Reply:
Agents still feel it, in view2 modify the code directly after the method call view1 be updated when the data back to view1 ready.
Reply:
If it is to restore the original data can also be considered undomanager. In ios, there simpleundo examples
Reply:
You can not view1's - (void) viewWillAppear: handle it?
If not, then, can only be custom fallback processing, and using the notification center NSNotificationCenter to achieve