public static async Task PopulateStationsCache()
{
if (StationsCache.Stations != null)
{
return;
}
if (File.Exists(StationsCache.cachePath))
{
IList <Station> stationsFromFile = FetchStationsFromFile();
StationsCache.Stations = stationsFromFile;
}
if (StationsCache.Stations != null)
{
Console.WriteLine("Populated stations cache from file system.");
return;
}
IList <Station> stationsFromServer = await FetchStationsFromServer();
StationsCache.Stations = new Collection <Station>(stationsFromServer);
Console.WriteLine("Populated stations cache from web service.");
// TODO: Write file cache asynchronously?
StationsCache.WriteFileCache(stationsFromServer);
}
public override void DidEnterBackground(UIApplication application)
{
// Use this method to release shared resources, save user data, invalidate timers and store the application state.
// If your application supports background exection this method is called instead of WillTerminate when the user quits.
Console.WriteLine("DidEnterBackground: Clearing stations cache.");
StationsCache.ClearStationsCache();
}
public override void DidReceiveMemoryWarning()
{
base.DidReceiveMemoryWarning();
// Release any cached data, images, etc that aren't in use.
Console.WriteLine("DidReceiveMemoryWarning: Clearing stations cache.");
StationsCache.ClearStationsCache();
}
public async override void OnActivated(UIApplication application)
{
// Restart any tasks that were paused (or not yet started) while the application was inactive.
// If the application was previously in the background, optionally refresh the user interface.
Console.WriteLine("OnActivated: Populating stations cache.");
await StationsCache.PopulateStationsCache();
Console.WriteLine("OnActivated: Populated stations cache.");
}