For iOS (Cocoa Touch), it\'s possible to go to your main.m and replace the fourth argument in UIApplicationMain(int argc, char *argv[], nil, nil) with the class nam
You can use setDelegate method of NSApplication instance. Here is a sample:
AppDelegate * delegate = [[AppDelegate alloc] init];
[[NSApplication sharedApplication] setDelegate:delegate];
[NSApp run];
As for return value you can use EXIT_SUCCESS
Subclass NSApplication, declare your subclass's name as the Application Class (or similar) property in Xcode. In your subclass you may override some function that gets called when the app is initialized, maybe -finishLaunching?