some problems we meet after implement IAP

1. IAP auto-renewable
in practice
Cocoaheads Taipei ,2016.12

2. 2

3. 3
In App Purchase
Users use their Apple ID purchase virtual product(s)
Developer use receipt(s) to implement business logic
Financial receive simple report

4. 4
step 1~7
get products user can purchase

5. 5

6. 6
NSSet *productsIDSet = ["product_identifiers1","product_identifiers2"]
self.productRequest = [[SKProductsRequest alloc]
initWithProductIdentifiers:productsIDSet];
productRequest.delegate = self;
[productRequest start];

7. 7
SKProductsRequestDelegate
- (void)productsRequest:(SKProductsRequest *)request
didReceiveResponse:(SKProductsResponse *)response
{
NSLog(@"receive products %@", response.products);
NSLog(@"invalidProductIdentifiers %@", response.invalidProductIdentifiers);
self.products = response.products;
……
}
[SKProduct] from productsIDSet

8. 8
step 8
user select product to buy

9. 9
step 8
user select product to buy
- (void)purchaseProduct:(SKProduct *)inProduct
{
SKPayment *p = [SKPayment paymentWithProduct:inProduct];
[[SKPaymentQueue defaultQueue] addPayment:p];
}

10. 10
step 9 ~11
validate user AppleID/password

11. 11
step 12 ~14
receive receipt

12. 12
SKPaymentTransactionObserver
- (void)paymentQueue:(SKPaymentQueue *)queue
updatedTransactions:(NSArray *)transactions
{
NSMutableArray *purchasedTransactions = [NSMutableArray array];
for (SKPaymentTransaction *t in transactions) {
switch (t.transactionState) {
case SKPaymentTransactionStatePurchased:
[purchasedTransactions addObject:t];
[[SKPaymentQueue defaultQueue] finishTransaction:t];
break;
//ignore other case in sample code
}
}
if ([purchasedTransactions count] > 0) {
//handle receipts here,continue step 15
}
}

13. 13
step 15~19
verify receipt with Apple server / Your server

14. 14
How server validate a receipt
1.Apple API
receipt product_id
receipt bid
receipt duration(auto-renewable)
https://sandbox.itunes.apple.com/verifyReceipt
https://buy.itunes.apple.com/verifyReceipt
2.DB
ensure receipt transaction_id not used

15. 15
step 20
Deliver purchased content

16. 16
Overview (bad side)
3.1.1 In-App Purchase, 3.1.2 Subscriptions:
If you want to unlock features or functionality within your app,you must use in-app purchase
only verify API, no webhook
When user cancel on iTunes ,Server will not get cancel request.
Can not know which Apple ID user use
Can not know purchase condition until receive receipt

17. 17
A lot of problems we met

18. 18
Receive sandbox receipt on production environment
production validate API ->
receive 21007 status code ->
try sandbox API
Solution:

19. 18
Receive sandbox receipt on production environment
production validate API ->
receive 21007 status code ->
try sandbox API
Solution:
Look like workaround,but it’s spec

20. 19
Critical:Network condition bad When Upload receipt to server

21. 19
Critical:Network condition bad When Upload receipt to server
Business logic
Purchase
Manager
Purchase
Manager
StoreKit
Purchase
ViewController
SKProductsRequestDelegate
SKPaymentTransactionObserverdelegatedelegate
Solution:
cache receipts , remove cache after ensure receipt is uploaded

22. 19
Critical:Network condition bad When Upload receipt to server
Business logic
Purchase
Manager
Purchase
Manager
StoreKit
Purchase
ViewController
SKProductsRequestDelegate
SKPaymentTransactionObserverdelegatedelegate
cache receipts
Solution:
cache receipts , remove cache after ensure receipt is uploaded

23. 19
Critical:Network condition bad When Upload receipt to server
Business logic
Purchase
Manager
Purchase
Manager
StoreKit
Purchase
ViewController
SKProductsRequestDelegate
SKPaymentTransactionObserverdelegatedelegate
cache receipts
trigger API
remove receipts
Solution:
cache receipts , remove cache after ensure receipt is uploaded

24. 19
Critical:Network condition bad When Upload receipt to server
Business logic
Purchase
Manager
Purchase
Manager
StoreKit
Purchase
ViewController
SKProductsRequestDelegate
SKPaymentTransactionObserverdelegatedelegate
cache receipts
trigger API
remove receipts
UI
Solution:
cache receipts , remove cache after ensure receipt is uploaded

25. 20
User purchase on iTunes instead of app
case 1
1.touch purchase product on App
2.when validate AppleID, type wrong password more than 3 times
3.StoreKit ask user to change password
4.redirect to iTunes
5.type correct password and user can purchase on iTunes

26. 21
User purchase on iTunes instead of app
touch this
itms-apps://buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/manageSubscriptionscase 2

27. 22
User purchase on iTunes instead of app
case 2 https://buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/manageSubscriptions
touch this

28. 23
User purchase on iTunes instead of app
Business logic
Purchase
Manager
Purchase
Manager
StoreKit
Purchase
ViewController
SKProductsRequestDelegate
SKPaymentTransactionObserverdelegate
delegate
Solution: init purchase manager at app launch

29. 23
User purchase on iTunes instead of app
Business logic
Purchase
Manager
Purchase
Manager
StoreKit
Purchase
ViewController
SKProductsRequestDelegate
SKPaymentTransactionObserverdelegate
delegate
Solution: init purchase manager at app launch
AppDelegate init at app launch

30. 24
What is receipt (app side)
SKPaymentTransaction
@property(nonatomic, readonly, nullable) NSData *transactionReceipt
/* base64 encode string */
NSString *receiptString = [receipt base64EncodedStringWithOptions:0];

31. 24
What is receipt (app side)
SKPaymentTransaction
@property(nonatomic, readonly, nullable) NSData *transactionReceipt
/* base64 encode string */
NSString *receiptString = [receipt base64EncodedStringWithOptions:0];

32. 25
What is receipt (server side)

33. 25
What is receipt (server side)

34. 25
What is receipt (server side)

35. 26
Critical: Auto-renew fail but user receive charge mail

36. 26
Critical: Auto-renew fail but user receive charge mail
Solution: Trigger Verify API at Next day of expire_date
Not the same day

37. 27
When switch from objC to swift

38. 28
When switch from objC to swift

39. 28
When switch from objC to swift
transactionReceipt property missing
can only use iOS 7 style receipt

40. 29
iOS 7 receipt

41. 29
iOS 7 receipt

42. 29
iOS 7 receipt

43. 30
iOS 7 receipt

44. 30
iOS 7 receipt

45. 31
iOS 6 vs iOS 7 style transaction receipts
• each transaction has unique iOS 6 style receipt
• iOS 7 style receipt get all receipt data in one query
• base64 encode iOS 7 style receipt is much larger than iOS 6 style

46. 32
Will original_transaction_id change?
purchase cancel purchase
again
A C
renew
a long time
B

47. 32
Will original_transaction_id change?
purchase cancel purchase
again
A C
original_transaction_id in receipt A , B and C keep the same
renew
a long time
B

48. 33
Can I manage auto-renewable subscription in Sandbox ?
No.
In addition,sandbox will auto-renew 5 times.
in the end will get 6 receipt

49. 34
What will user see in iTune Connect If my app have multiple auto-
renewable products( A & B)?

50. 34
What will user see in iTune Connect If my app have multiple auto-
renewable products( A & B)?
https://buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/
manageSubscriptions
This URL will only work for production accounts to display existing auto-renewing
subscriptions for management

51. 35
purchase
product A in app
cancel
auto-renew A
in iTune
purchase
product B in app
product A
expire
What will user see in iTune Connect If my app have multiple auto-
renewable products( A & B)?

52. 35
purchase
product A in app
cancel
auto-renew A
in iTune
purchase
product B in app
product A
expire
What will user see in iTune Connect If my app have multiple auto-
renewable products( A & B)?
iTune display product A product B

53. 36
You can not do anything If
You have a auto renewable product,also set trial period(Eq:1 month)
But Apple receipt trial period is more than your setting
KKTV happen this few times

54. 37
if your service has
account system + multiple platform + multiple payment

55. 37
if your service has
account system + multiple platform + multiple payment
email
facebook
phone number
iOS
Android
Web
PS4
…
IAP
credit card
mobile payment
POSA card
redeem code
convenient store code

56. 38
Example:
User Apple ID KKTV
iTunes
KKTV
Result:
StoreKit

57. 39
Example:
User Apple ID KKTV
iTunes
KKTV
Result:
receipt server
KKTV
Solution:
receipt Alert

58. 39
Example:
User Apple ID KKTV
iTunes
KKTV
Result:
receipt server
KKTV
Solution:
receipt Alert

59. 40
Example:
user IAP
iTunes IAP

60. 40
Example:
user IAP
iTunes IAP
Result
IAP user

61. 40
Example:
user IAP
iTunes IAP
Result
IAP user
Solution
app/server side user iTunes

62. 41
Example:
user
IAP
..... KKTV
KKTV IAP

63. 41
Example:
user
IAP
Result
AppleID user
..... KKTV
KKTV IAP

64. 42
Financial
• report daily
• report user ID transactionID
• user cancel / refund
•

65. 43
Conclusion
• IAP is unfriendly to Developer. But super easy for user.
• Tracking IAP log help find unexpected problems
• Raise IAP price could be an option

66. 44
Reference
TN2387:In-App Purchase Best Practices
TN2413: In-App Purchase FAQ
In-App Purchase Programming Guide
Receipt Validation Programming Guide
WWDC 2016: Using StoreKit for In-App Purchases with Swift 3
WWDC 2014: Optimizing In-App Purchases
WWDC 2012: Selling Products with Store Kit
WWDC 2013: Using Store Kit for In-App Purchases
WWDC 2012: Managing Subscriptions with In-App Purchase
TN2259: Adding In-App Purchase to your iOS and macOS Applications
https://forums.developer.apple.com/community/system-frameworks/in-app-purchase