The delegates are only available with the object ads, check the API Documentation.
But you can use something like this:
RevMobFullscreen *ad = [[RevMobAds session] fullscreen];
ad.delegate = self;
[ad showAd];
Or you can use the new block "delegates":
RevMobFullscreen *ad = [[RevMobAds session] fullscreen];
[ad loadWithSuccessHandler:^(RevMobFullscreen *fs) {
[fs showAd];
NSLog(@"Ad loaded");
} andLoadFailHandler:^(RevMobFullscreen *fs, NSError *error) {
NSLog(@"Ad error: %@",error);
} onClickHandler:^{
NSLog(@"Ad clicked");
} onCloseHandler:^{
NSLog(@"Ad closed");
}];