public async Task<string> ApplicationDataFolder()
{
if (string.IsNullOrWhiteSpace(this.cachedAppDataFolder))
{
var root = ApplicationData.Current.LocalFolder;
var newFolder = await root.CreateFolderAsync("ApplicationState", CreationCollisionOption.OpenIfExists);
this.cachedAppDataFolder = newFolder.Path;
}
return this.cachedAppDataFolder;
}