private async void Button_OnClicked(object sender, EventArgs e)
{
string currency = null;
var selectedIndex = CurrencyPicker.SelectedIndex;
if (selectedIndex != -1)
{
currency = CurrencyPicker.Items[selectedIndex];
}
var amountInput = AmountEntry.Text;
var amount = decimal.Parse(amountInput);
var result = await ConvertManager.ConvertCurrency(currency, amount);
await DisplayAlert("Success!", amount + " Bitcoins is: " + result.ToString(CultureInfo.InvariantCulture) + currency, "Close");
}