ios - Parse.com チェック friendRequest 重複 iOS

Question

Parse.comとCloud CodeまたはiOS Codeとの重複は避けたいと思います。データベースからの私のクラスは次のとおりです。

" from " userId が既に " to " userId に送信している場合、2 番目の friendRequest は送信されません。

これが私のiOSコードです:

PFUser *selectedUser = [self.allUsers objectAtIndex:indexPath.row];
//request them
PFObject *friendRequest = [PFObject objectWithClassName:@"FriendRequest"];
friendRequest[@"from"] = self.currentUser;
friendRequest[@"fromUsername"] = [[PFUser currentUser] objectForKey:@"username"];
//selected user is the user at the cell that was selected
friendRequest[@"to"] = selectedUser;
// set the initial status to pending
friendRequest[@"status"] = @"pending";
[friendRequest saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {

    if (succeeded) {


        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sent !" message:@"Friend request sent" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alert show];



    } else {

        // error occurred
    }
}];