App crashing when buying in-app purchase - ios

Question

My app crashes sometimes when buying something with in-app purchase.
Most of the time it works fine but sometimes the app crashes without any error (I am testing in debug mode).
To set-up the in-app purchase (non-consumable), I used the following example:
https://github.com/conceptdev/xamarin-samples/tree/master/InAppPurchase/NonConsumables
The class which handles the in-app purchase looks like this:
public class InAppPurchaseManager : SKProductsRequestDelegate {
public static NSString InAppPurchaseManagerProductsFetchedNotification = new NSString("InAppPurchaseManagerProductsFetchedNotification");
public static NSString InAppPurchaseManagerTransactionFailedNotification = new NSString("InAppPurchaseManagerTransactionFailedNotification");
public static NSString InAppPurchaseManagerTransactionSucceededNotification = new NSString("InAppPurchaseManagerTransactionSucceededNotification");
public static NSString InAppPurchaseManagerRequestFailedNotification = new NSString("InAppPurchaseManagerRequestFailedNotification");
SKProductsRequest productsRequest;
CustomPaymentObserver theObserver;
SKProduct[] products;
public static NSAction Done {get;set;}
public InAppPurchaseManager ()
{
theObserver = new CustomPaymentObserver(this);
SKPaymentQueue.DefaultQueue.AddTransactionObserver(theObserver);
}
// received response to RequestProductData - with price,title,description info
public override void ReceivedResponse (SKProductsRequest request, SKProductsResponse response)
{
products = response.Products;
NSDictionary userInfo = null;
if (products.Length > 0) {
NSObject[] productIdsArray = new NSObject[response.Products.Length];
NSObject[] productsArray = new NSObject[response.Products.Length];
for (int i = 0; i < response.Products.Length; i++) {
productIdsArray[i] = new NSString(response.Products[i].ProductIdentifier);
productsArray[i] = response.Products[i];
}
userInfo = NSDictionary.FromObjectsAndKeys (productsArray, productIdsArray);
}
NSNotificationCenter.DefaultCenter.PostNotificationName(InAppPurchaseManagerProductsFetchedNotification,this,userInfo);
foreach (string invalidProductId in response.InvalidProducts) {
Console.WriteLine("Invalid product id: " + invalidProductId );
}
}
// request multiple products at once
public void RequestProductData (List<string> productIds)
{
var array = new NSString[productIds.Count];
for (var i = 0; i < productIds.Count; i++) {
array[i] = new NSString(productIds[i]);
}
NSSet productIdentifiers = NSSet.MakeNSObjectSet<NSString>(array);
//set up product request for in-app purchase
productsRequest = new SKProductsRequest(productIdentifiers);
productsRequest.Delegate = this; // SKProductsRequestDelegate.ReceivedResponse
productsRequest.Start();
Console.WriteLine ("BEREIKT");
}
// Verify that the iTunes account can make this purchase for this application
public bool CanMakePayments()
{
return SKPaymentQueue.CanMakePayments;
}
public void PurchaseProduct(string appStoreProductId)
{
Console.WriteLine("PurchaseProduct " + appStoreProductId);
SKPayment payment = SKPayment.PaymentWithProduct (appStoreProductId);
SKPaymentQueue.DefaultQueue.AddPayment (payment);
}
public void CompleteTransaction (SKPaymentTransaction transaction)
{
Console.WriteLine ("CompleteTransaction " + transaction.TransactionIdentifier);
var productId = transaction.Payment.ProductIdentifier;
// Register the purchase, so it is remembered for next time
//PhotoFilterManager.Purchase(productId);
UserDefaults.Purchase(productId);
FinishTransaction (transaction, true);
//Show Dialog
new UIAlertView("Succes", "De aankoop is gelukt." +
"\n Je kunt de gekozen categorieën nu spelen.", null, "OK", null).Show();
/*
if (ReceiptValidation.VerificationController.SharedInstance.VerifyPurchase (transaction)) {
Console.WriteLine ("Verified!");
// Register the purchase, so it is remembered for next time
PhotoFilterManager.Purchase(productId);
FinishTransaction (transaction, true);
} else {
Console.WriteLine ("NOT Verified :(");
FinishTransaction (transaction, false);
}
*/
}
public void RestoreTransaction (SKPaymentTransaction transaction)
{
// Restored Transactions always have an 'original transaction' attached
Console.WriteLine("RestoreTransaction " + transaction.TransactionIdentifier + "; OriginalTransaction " + transaction.OriginalTransaction.TransactionIdentifier);
var productId = transaction.OriginalTransaction.Payment.ProductIdentifier;
// Register the purchase, so it is remembered for next time
//PhotoFilterManager.Purchase(productId); // it's as though it was purchased again
UserDefaults.Purchase(productId);
FinishTransaction(transaction, true);
}
public void FailedTransaction (SKPaymentTransaction transaction)
{
//SKErrorPaymentCancelled == 2
if (transaction.Error.Code == 2) // user cancelled
Console.WriteLine("User CANCELLED FailedTransaction Code=" + transaction.Error.Code + " " + transaction.Error.LocalizedDescription);
else // error!
Console.WriteLine("FailedTransaction Code=" + transaction.Error.Code + " " + transaction.Error.LocalizedDescription);
FinishTransaction(transaction,false);
//Show Dialog
new UIAlertView("Helaas", "De aankoop is mislukt." +
"\n Probeer het op een later tijdstip nogmaals a.u.b.", null, "OK", null).Show();
}
public void FinishTransaction(SKPaymentTransaction transaction, bool wasSuccessful)
{
Console.WriteLine("FinishTransaction " + wasSuccessful);
// remove the transaction from the payment queue.
SKPaymentQueue.DefaultQueue.FinishTransaction(transaction); // THIS IS IMPORTANT - LET'S APPLE KNOW WE'RE DONE !!!!
using (var pool = new NSAutoreleasePool()) {
NSDictionary userInfo = NSDictionary.FromObjectsAndKeys(new NSObject[] {transaction},new NSObject[] {new NSString("transaction")});
if (wasSuccessful) {
// send out a notification that we’ve finished the transaction
NSNotificationCenter.DefaultCenter.PostNotificationName(InAppPurchaseManagerTransactionSucceededNotification,this,userInfo);
} else {
// send out a notification for the failed transaction
NSNotificationCenter.DefaultCenter.PostNotificationName(InAppPurchaseManagerTransactionFailedNotification,this,userInfo);
}
}
}
/// <summary>
/// Probably could not connect to the App Store (network unavailable?)
/// </summary>
public override void RequestFailed (SKRequest request, NSError error)
{
Console.WriteLine (" ** InAppPurchaseManager RequestFailed() " + error.LocalizedDescription);
using (var pool = new NSAutoreleasePool()) {
NSDictionary userInfo = NSDictionary.FromObjectsAndKeys(new NSObject[] {error},new NSObject[] {new NSString("error")});
// send out a notification for the failed transaction
NSNotificationCenter.DefaultCenter.PostNotificationName(InAppPurchaseManagerRequestFailedNotification,this,userInfo);
}
}
/// <summary>
/// Restore any transactions that occurred for this Apple ID, either on
/// this device or any other logged in with that account.
/// </summary>
public void Restore()
{
Console.WriteLine (" ** InAppPurchaseManager Restore()");
// theObserver will be notified of when the restored transactions start arriving <- AppStore
SKPaymentQueue.DefaultQueue.RestoreCompletedTransactions();
}
}
What could cause the crash?
FYI: I am using Xamarin iOS version 6.3.4.36 (beta). For now I use this beta version because it solves a problem I have with Game Center. The stable version of Xamarin does not solve this yet.
PS. I read that the example I used not implemented RECEIPT VERIFICATION. What does this mean and is this necessary to implement?
FIRST UPDATE:
Sometimes I get this error.
mono-rt: Stacktrace:
mono-rt: at <unknown> <0xffffffff>
mono-rt: at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
mono-rt: at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x0004c] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:38
mono-rt: at PP_IOS.Application.Main (string[]) [0x00001] in /Users/Mac01/Projects/PP/PP_IOS/Main.cs:19
mono-rt: at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>
mono-rt:
Native stacktrace:
mono-rt:
=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================
And another time I get this error:
mono-rt: Stacktrace:
mono-rt: at <unknown> <0xffffffff>
mono-rt: at (wrapper managed-to-native) MonoTouch.ObjCRuntime.Messaging.void_objc_msgSend_IntPtr (intptr,intptr,intptr) <IL 0x00025, 0xffffffff>
mono-rt: at MonoTouch.StoreKit.SKPaymentQueue.AddPayment (MonoTouch.StoreKit.SKPayment) [0x0001c] in /Developer/MonoTouch/Source/monotouch/src/StoreKit/SKPaymentQueue.g.cs:107
mono-rt: at PP_IOS.InAppPurchaseManager.PurchaseProduct (string) [0x0001f] in /Users/Mac01/Projects/PP/PP_IOS/Utils/InAppPurchase/InAppPurchaseManager.cs:109
mono-rt: at PP_IOS.UpgradeScreen.<BuyCategoryArtistsAndSports>m__21 () [0x0003d] in /Users/Mac01/Projects/PP/PP_IOS/ControllersUniversal/UpgradeScreen.cs:171
mono-rt: at MonoTouch.Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Developer/MonoTouch/Source/monotouch/src/shared/Foundation/NSAction.cs:87
mono-rt: at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <IL 0x0004e, 0xffffffff>
mono-rt: at <unknown> <0xffffffff>
mono-rt: at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
mono-rt: at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x0004c] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:38
mono-rt: at PP_IOS.Application.Main (string[]) [0x00001] in /Users/Mac01/Projects/PP/PP_IOS/Main.cs:19
mono-rt: at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>
mono-rt:
Native stacktrace:
mono-rt:
=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================
SECOND UPDATE
I just found the way the problem occurs. The buttons to buy and restore an in-app purchase are displayed in a modal view. It seems that the app crashes when I reopen the modal view and tap at the buy or restore button. So when I open the modal view for the first time and I tap at the buy and restore buttons it (most of the time) works fine. But when I reopen the modal view, and I tap at the buy or restore button, the app crashes with the error showed above.
Somebody familiar with this?

Answer 1

Problem solved!
I had to remove the TransactionObserver when closing the view.
public override void ViewWillDisappear (bool animated)
{
base.ViewWillDisappear (animated);
//Prevents crash when re-opening view
SKPaymentQueue.DefaultQueue.RemoveTransactionObserver (theObserver);
}

Answer 2

Ok, this is really dumb. I would go ahead and pull out a stamp and pen to get that strongly-worded letter to Tim Cook started.
I found from experience that SKProductsRequestDelegate.RequestFailed can occasionally return a null NSError. This would cause a null reference exception on the first line of your method. This is pretty terrible, and I'm not sure why it happens.
You might change your code to this:
public override void RequestFailed (SKRequest request, NSError error)
{
if (error == null)
Console.WriteLine("NSError is null!");
else
Console.WriteLine (" ** InAppPurchaseManager RequestFailed() " + error.LocalizedDescription);
using (var pool = new NSAutoreleasePool()) {
NSDictionary userInfo = NSDictionary.FromObjectsAndKeys(new NSObject[] {error},new NSObject[] {new NSString("error")});
// send out a notification for the failed transaction
NSNotificationCenter.DefaultCenter.PostNotificationName(InAppPurchaseManagerRequestFailedNotification,this,userInfo);
}
}
Make sure you account for it on the other end of the NSNotificationCenter, too.
BTW, I don't know what all that NSAutoreleasePool jazz is for--you should remove it. Did you get this from a really old MonoTouch example?

Answer 3

I have had the same issue also. I found that having
[[SKPaymentQueue defaultQueue] removeTransactionObserver:self];
in the viewDidUnload does not work. It needs to be in viewWillDisappear. That appears to have fixed it for me.