storekit - iOS: How to put a button on the top of SKStoreProductViewController -

i want put custom button on top of skstoreproductviewcontroller. tried below did not work. wondering if give me advices.

skstoreproductviewcontroller *storeviewcontroller = [[skstoreproductviewcontroller alloc] init];  uibarbuttonitem *sharebutton = [[uibarbuttonitem alloc] initwithbarbuttonsystemitem:uibarbuttonsystemitemaction                                                                              target:self                                                                              action:@selector(showsharedialog)]; storeviewcontroller.navigationitem.rightbarbuttonitem = sharebutton;  storeviewcontroller.delegate = self; [self presentviewcontroller:storeviewcontroller animated:yes completion:^() {     [storeviewcontroller loadproductwithparameters:@{skstoreproductparameteritunesitemidentifier:appid}                                    completionblock:^(bool result, nserror *error) {}]; }];