Object C Two delegates have the same function name: Duplicate declaration of method 'interstitialDidReceiveAd:'

GADInterstitialDelegate & IMInterstitialDelegate have the same function name: interstitialDidReceiveAd

//inmob
- (void)interstitialDidReceiveAd:(IMInterstitial *)ad
                        //callback:(id<IMInterstitialDelegate>)callback
{
    [ad presentInterstitialAnimated:YES];
      NSLog(@"!!! inmob interstitialDidReceiveAd ok ");
}

// Sent when an interstitial ad request failed
- (void)interstitial:(IMInterstitial *)ad didFailToReceiveAdWithError:(IMError *)error
            //callback:(id<IMInterstitialDelegate>)callback
{
        NSLog(@"!!! inmob didFailToReceiveAdWithError ");
   // NSString *errorMessage = [NSString stringWithFormat:@"Loading ad (%@) failed. Error code: %d, message: //%@", [self.detailItem objectForKey:@"title"], [error code], [error localizedDescription]];
    //NSLog(@"%@", errorMessage);
}

//admob
- (void)interstitialDidReceiveAd:(GADInterstitial *)interstitialAdmob
{
    NSLog(@"!!! admob interstitialDidReceiveAd ok");
}

- (void)interstitial:(GADInterstitial *)interstitial
            //callback:(id<GADInterstitialDelegate>)callback
didFailToReceiveAdWithError:(GADRequestError *)error
{
    NSLog(@"!!!!!!! admob interstitial error!");
}

Build error: Duplicate declaration of method 'interstitialDidReceiveAd:'

Objective-C doesn't allow multiple methods with the same name but accepting different types. Luckily it is also weakly typed. So you should be able to get away with:

- (void)interstitialDidReceiveAd:(id)interstitial
{
    if([interstitial isKindOfClass:[GADInterstitial class]])
        [self admobInterstitialDidReceiveAd:interstitial];
    else
        [self inmobiInterstitialDidReceiveAd:interstitial];
}

Or any such more thorough test based on receiving an id and checking its type when it arrives.