ItemTouchHelper用法:

        // COMPLETED (3) Create a new ItemTouchHelper with a SimpleCallback that handles both LEFT and RIGHT swipe directions
        // Create an item touch helper to handle swiping items off the list
        new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {

            // COMPLETED (4) Override onMove and simply return false inside
            @Override
            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                //do nothing, we only care about swiping
                return false;
            }

            // COMPLETED (5) Override onSwiped
            @Override
            public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
                // COMPLETED (8) Inside, get the viewHolder's itemView's tag and store in a long variable id
                //get the id of the item being swiped
                long id = (long) viewHolder.itemView.getTag();
                // COMPLETED (9) call removeGuest and pass through that id
                //remove from DB
                removeGuest(id);
                // COMPLETED (10) call swapCursor on mAdapter passing in getAllGuests() as the argument
                //update the list
                mAdapter.swapCursor(getAllGuests());
            }

            //COMPLETED (11) attach the ItemTouchHelper to the waitlistRecyclerView
        }).attachToRecyclerView(waitlistRecyclerView);