private async Task QuerySubscriptions() { if (subscriptionPage == 1) { if (SubscriptionItems == null) { SubscriptionItems = new ObservableCollection <SubscriptionItem>(); } else { SubscriptionItems.Clear(); } } UserContentProvider user = new UserContentProvider(); List <Subscription> reuslt = await user.QuerySubscription(subscriptionPage, currentUserId, GlobalValue.CurrentUserContext.UserId, GlobalValue.CurrentUserContext.MobileToken); reuslt.ForEach(x => SubscriptionItems.Add(ConvertToSubscriptionItem(x))); subscriptionPage++; if (SubscriptionItems.Count <= 10 && subscriptionPage == 2) { await QuerySubscriptions(); } }