ListView for Xamarin.Android: SwipeRefreshBehavior

If your list contains items, which may change after the initial list has been loaded, it may be good idea to allow the users to refresh the list. That is easy with the SwipeRefreshBehavior. Simply add an instance of this behavior to your list view and you will get a nice indicator that will be shown when the user swipes the list from its top.

Getting Started

If you have read the Getting Started page, you already have a project with RadListView which is populated with items of type City. In the Behaviors Overview we introduced the behaviors and now we will go into more details about the SwipeRefreshBehavior. Here's how to add the SwipeRefreshBehavior to your list view instance:

SwipeRefreshBehavior swipeRefreshBehavior = new SwipeRefreshBehavior ();
listView.AddBehavior (swipeRefreshBehavior);

This will show a loading indicator when the user swipes from the top of the list, but in order to actually refresh the list you will need to add a SwipeRefreshListener.

SwipeRefreshListener

The SwipeRefreshListener should be used to get notification that refresh is requested. Here's one simple implementation:

public class SwipeListener : Java.Lang.Object, SwipeRefreshBehavior.ISwipeRefreshListener {
    private CityAdapter cityAdapter;
    public SwipeListener(CityAdapter adapter) {
        cityAdapter = adapter;
    }
    public void OnRefreshRequested ()
    {
        cityAdapter.RefreshList ();
        cityAdapter.NotifyRefreshFinished ();
    }
}

You will also need to create the refreshList() method in your adapter in order to actually refresh the list. That method's implementation will depend on the way you load your data, but for this example we can leave its body empty with the presumption that our initial list will not change over the time. Pay attention to the call of the notifyRefreshFinished() which is one of the options to notify the behavior that the refresh operation is complete. The other option is to call SwipeRefreshBehavior's endRefresh() method and the effect will be the same — the loading indicator will hide.

Now we can add the listener to our behavior:

SwipeListener swipeRefreshListener = new SwipeListener ();
swipeRefreshBehavior.AddListener(swipeRefreshListener)

The indicator that this behavior uses is actually the SwipeRefreshLayout from the support library. You can get the instance of this layout with the swipeRefresh() method in case you need to apply any customizations to this layout, for example, change the indicator's color.