CompletionHandler typedef

CompletionHandler = Future<void> Function(bool delete)

If you want the animation I support you should modify your data source first,then wait handler to execute,after that, you can call setState to update your UI.

Code Example:

 initState() {
   List list = [1,2,3,5];
 }

 onTap(handler) async {
   list.removeAt(2);

   // true: will delete this row in ListView
   // false: will not delete it
   // Q: When to use "await"?
   // A: The time when you want animation
   await handler(true or false);

   setState((){});
 }

Implementation

typedef CompletionHandler = Future<void> Function(bool delete);