How do I read receipt data with existing paid iOS app? - ios

Question

I have a paid app that I'm thinking about making free with in app purchases. If I make the switch I'll need to check if the user has already paid for the app and then enable the paid features.
I think the below code should do what I need but I'm not sure how to test it. I built the app and ran it using my development provisioning profile on my device and receitpData is empty. So I built the app with a distribution provisioning profile and submitted it to the app store then downloaded the app using test flight but I'm still having the same problem.
How do I get the receipt data from an existing app?
Do I need to enable in-app purchases for this app to get this data?
NSURL *receiptUrl = [[NSBundle mainBundle] appStoreReceiptURL];
NSData *receiptData = [NSData dataWithContentsOfURL:receiptUrl];

Answer 1

I figured it out:
#import <StoreKit/StoreKit.h>
Don't forget to add its delegates
<SKPaymentTransactionObserver, SKProductsRequestDelegate>
Here's the code:
SKReceiptRefreshRequest* request = [[SKReceiptRefreshRequest alloc] initWithReceiptProperties:nil];
request.delegate = self;
[request start];
and then:
-(void)requestDidFinish:(SKRequest*)request{
if([request isKindOfClass:[SKReceiptRefreshRequest class]]){
NSLog(#"YES, You purchased this app");
}
}
- (void)request:(SKRequest*)request didFailWithError:(NSError *)error{
NSLog(#"NO, you need to buy it");
}