RefreshCallback typedef Null safety

RefreshCallback = Future<void> Function()

A callback function that's invoked when the CupertinoSliverRefreshControl is pulled a refreshTriggerPullDistance. Must return a Future. Upon completion of the Future, the CupertinoSliverRefreshControl enters the RefreshIndicatorMode.done state and will start to go away.

Implementation

typedef RefreshCallback = Future<void> Function();