public void SetMap( 
   Map map
)

//Set the map that is associated with a map frame.

//Perform on worker thread
await QueuedTask.Run(() =>
{
  mf.SetMap(map);
});

//Change the map associated with a map frame

//Reference a map frame on a layout
MapFrame mfrm = layout.FindElement("Map Frame") as MapFrame;

//Perform on worker thread
await QueuedTask.Run(() =>
{
  //Reference map from the project item 
  Map map = Project.Current.GetItems<MapProjectItem>().FirstOrDefault(m => m.Name.Equals("Map1")).GetMap();

  //Set the map to the map frame
  mfrm.SetMap(map);
});