What method is called when application is resume ?

On iPhone when you press the home button the application runs on background, or something like that.
What method is called on the application when is started again by clicking on it’s icon ?

I want to know this because I have background and sound buttons which I need to set to enabled or disabled based on user’s choice.
I want to resume or not resume the sound when the application is started again.

Regards,
Adrian

You can refer HelloWolrd/Classes/AppDelegate.cpp.
AppDelegate::applicationWillEnterForeground() is called when application is resume.