public CurrencyVM()
{
Title = "Валюта";
Currencies = new ObservableCollection <Currency>();
LoadItemsCommand = new Command(async() => await ExecuteLoadItemsCommand());
MessagingCenter.Subscribe <NewCurrencyPage, Currency>(this, "AddCurrency", async(obj, item) =>
{
var newItem = item as Currency;
Currencies.Add(newItem);
await repository.AddItemAsync(newItem);
});
}