UIApplicationMain

int UIApplicationMain (

   int argc,

   char *argv[],

   NSString *principalClassName,

   NSString *delegateClassName

);

argc The count of arguments in argv; this usually is the corresponding parameter to main. argv A variable list of arguments; this usually is the corresponding parameter to main. principalClassName The name of the UIApplication class or subclass. If you specify nil, UIApplication is assumed. delegateClassName The name of the class from which the application delegate is instantiated. If principalClassName designates a subclass of UIApplication, you may designate the subclass as the delegate; the subclass instance receives the application-delegate messages. Specify nil if you load the delegate object from your application’s main nib file. 여기서, delegateClassName 파라미터를 통해, 우리의 어플리케이션을 커스텀 할 수 있는 것이다.