iOS ขอสอบถามการทำแบ่งหน้าแบบ load ข้อมุลเป็นช่วงๆของ app จากข้อมูล json

lstView1.setOnScrollListener(new OnScrollListener() {

			@Override
			public void onScrollStateChanged(AbsListView view, int scrollState) {

				int threshold = 1;
				int count = lstView1.getCount();
				numlist = count;

				if (scrollState == SCROLL_STATE_FLING) {

				} else if (scrollState == SCROLL_STATE_IDLE) {

					if (lstView1.getLastVisiblePosition() >= count - threshold) {
						// Execute LoadMoreDataTask AsyncTask
						start_ += 20;
						end_ += 20;
						new DownloadJSONAsync().execute();
					}

				} else if (scrollState == SCROLL_STATE_TOUCH_SCROLL) {

				}
			}

			@Override
			public void onScroll(AbsListView view, int firstVisibleItem,
					int visibleItemCount, int totalItemCount) {

			}
		});