example of parsing a receipt for an in-app purchase using iOS Xamarin? - xamarin.ios

Question

I am trying to implement purchase validation for my app. I see that I can send the purchase receipt to my server to verify with Apple. However, I cannot figure out the correct way to POST the NSData to my URL for validation. Something like this:
public void CompleteTransaction (SKPaymentTransaction transaction) {
var productId = transaction.Payment.ProductIdentifier;
NSUrl receiptURL = NSBundle.MainBundle.AppStoreReceiptUrl;
NSData theData = NSData.FromUrl (receiptURL);
RestRequest request = new RestRequest(validationURL, Method.POST);
request.AddBody(theData); // ??
restClient.ExecuteAsync<bool>((response) =>
{
FinishTransaction(transaction, response.Data);
});
}
Does anyone have an example? I am using RestSharp.
Thanks!
davevr

Answer 1

OK, found how to do it. The trick was to parse the receipt into a dictionary and then pull the key out of that. Sample code:
public void CompleteTransaction (SKPaymentTransaction transaction) {
var productId = transaction.Payment.ProductIdentifier;
NSUrl receiptURL = NSBundle.MainBundle.AppStoreReceiptUrl;
NSData receipt = NSData.FromUrl (receiptURL);
// here is the code I was missing
NSDictionary requestContents = NSDictionary.FromObjectAndKey((NSString)receipt.GetBase64EncodedString(
NSDataBase64EncodingOptions.None),
(NSString)"receipt-data");
string receiptData = (requestContents["receipt-data"] as NSString).ToString();
RestRequest request = new RestRequest(<url to your server>, Method.POST);
request.AddParameter ("receipt-data", receiptData );
apiClient.ExecuteAsync<bool>(request, (response) =>
{
FinishTransaction (transaction, response.Data);
});
Once that is done, you can do the validation on the Apple server. There is lots of sample code on the net for that part.