I have an application with a class named "appliationAppDelegate" which is the delegate of my application. Most function are within that class. I also have the class applicationViewController because the method 'didReceiveMemoryWarning' must be inside this file. How can I execute a method that is located in the class 'appliationAppDelegate' from the method 'didReceiveMemoryWarning' which is located in 'applicationViewController'? Tried everything I could think of but still no good results... Thanks for your help PS. I've created those classes with Interface Builder.