The pull to refresh is a UI pattern long since present in mobile applications - it makes the user able to refresh the current view with a vertical swipe. It’s most commonly used in iOS apps, although it can also be found in quite a few Android apps. Not long ago Google made an Androidified version (first appeared in Google Now), where the refresh indicator is built into the ActionBar. Although a great library was available for a couple of months now (ActionBar-PullToRefresh by Chris Banes), Google added an official way to to achieve this effect to the Support Library v19.1.0, called SwipeRefreshLayout.
How to use the SwipeRefreshLayout
SwipeRefreshLayout is fairy easy to use, just wrap it around a vertically scrollable View (like a ListView or ScrollView) for it to work correctly. The following example uses a ListView.
The SwipeRefreshLayout takes care of detecting the vertical swipe, showing a progress animation on the ActionBar and also pushes down the layout. When a swipe occurs, the OnRefreshListener’s onRefresh() method is triggered.
It is possible to trigger multiple onRefresh() events while one is running, so you’ll have to take care of everything to work correctly (RxJava’s Subscription comes in handy). And while the refresh animation is triggered by a swipe, it will not stop when the task is finished, this has to be done manually with the setRefreshing() method. Calling this function at startup (when the items are loading for the first time, without the user explicitly refreshing) can be a good way of providing consistent experience instead of using a ProgressBar.
You can set the refresh indicator colors with the setColorScheme() method, which is a bit unflexible - the number of colors is always four, not more, not less. And an other thing: only resource identifiers supported, so the colors have to be defined in an xml, you can’t supply them in code.
The complete example can be found at this Gist.