UIActivityItemSource Protocole set complex object

I'm using iOS 6 new way to share information : UIActivityViewController. To select the shared data depending on the media (facebook, twitter or mail) my view controller implement the UIActivityItemSource Protocol as follow :

- (IBAction)onShareButton:(UIButton *)sender
{

    UIActivityViewController *activityViewController = [[UIActivityViewController alloc] initWithActivityItems:@[self] applicationActivities:nil];

    activityViewController.excludedActivityTypes = @[UIActivityTypeMessage, UIActivityTypeAssignToContact, UIActivityTypeCopyToPasteboard, UIActivityTypeMessage, UIActivityTypePostToWeibo, UIActivityTypePrint, UIActivityTypeSaveToCameraRoll];
    [self presentViewController:activityViewController animated:YES completion:^{}];
}

#pragma mark - UIActivityItemSource Protocol

- (id)activityViewController:(UIActivityViewController *)activityViewController itemForActivityType:(NSString *)activityType {
    if ([activityType isEqualToString:UIActivityTypePostToFacebook]) {
        NSArray *items = @[@"message facebook", [NSURL URLWithString:@"http://www.myUrlFacebook.com"]];
        return items;
    } else if ([activityType isEqualToString:UIActivityTypePostToTwitter]) {
        NSArray *items = @[@"message twitter", [NSURL     URLWithString:@"http://www.myUrlTwitter.com"]];
        return items;
    } else if ([activityType isEqualToString:UIActivityTypeMail]) {
        NSArray *items = @[@"message mail", [NSURL URLWithString:@"http://www.myUrlMail.com"]];
        return items;
    }

        NSArray *items = @[@"Not a proper Activity", [NSURL URLWithString:@"http://www.myUrlMail.com"]];
    return items;
}

- (id)activityViewControllerPlaceholderItem:(UIActivityViewController *)activityViewController {
    return @"PlaceHolder";
}

When I'm returning a simple NSString for activityViewController:itemForActivityType: the string is well used by my UIActivityViewController, but I can't find a way to use an Array !

According to Apple Documentation it should be possible :

This method returns the actual data object to be acted on by an activity object Apple documentation

Does anyone ever use this UIActivityItemSource Protocol with Arrays, or is there a use full tutorial to do that ?

Note : I also got this error on the console, it may help ...

Launch Services: Registering unknown app identifier com.apple.mobilemail failed

Launch Services: Unable to find app identifier com.apple.mobilemail

After spending a significant amount of time trying to figure this one out, it seems it isn't possible to pass it an NSArray of items. So I extended UIActivityViewController to make it possible.

RDActivityViewController