In terms of publicity or advertisement of an iOS app there is a feature where we can make our iOS app social or can share on facebook. Accepting a request from a app will direct the person to the Canvas Page URL of the app that sent the Request. For native mobile apps, accepting the request will direct the person to the app on their device if installed or to the appropriate location (Apple App Store) to download the app otherwise.

Method to be call is here...

[FBWebDialogs
 presentRequestsDialogModallyWithSession:nil
 message:@"Learn how to make your iOS apps social."
 title:nil
 parameters:nil
 handler:^(FBWebDialogResult result, NSURL *resultURL, NSError *error) {} ];

For more help see the attached code file.

Happy Coding...!!!