/// <summary>
/// Initializes an async process to purchas the product. Only one purchase request can be happening at a time
/// </summary>
/// <param name="productId">Product to buy</param>
/// <returns>Purchase object</returns>
public async Task <InAppPurchaseResult> PurchaseAsync(string productId)
{
// First, set the Completion Task Source. The Payment Observer will handle only one request at a time
TaskCompletionSource <InAppPurchaseResult> transactionPurchased = new TaskCompletionSource <InAppPurchaseResult>();
_paymentObserver.SetTransactionPurchasedTask(transactionPurchased);
SKPayment payment = SKPayment.CreateFrom(productId);
SKPaymentQueue.DefaultQueue.AddPayment(payment);
// Wait till the Task is complete (e.g. Succeeded or Failed - which will result in Exception)
return(await transactionPurchased.Task);
}
