Phonegap Plugin - append lines to app delegate

take a look into the Push Plugin, they use an objective-c category for the appDelegate

https://github.com/phonegap-build/PushPlugin

If you just want to be notified when the app becomes active you don't need to change anything on the AppDelegate, just put this on your plugin:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onAppDidBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:nil]; 

- (void)onAppDidBecomeActive:(NSNotification*)notification
{

     NSLog(@"%@",@"applicationDidBecomeActive");

}