How to fetch already purchased details of iOS IAP Auto Renewable product

I have created Auto renewable products and testing in sandbox environment. My question is I have purchased one product, and If I try to purchase same product with same Apple account it is showing alert as already purchased as expected but I could not able to fetch that transaction details as it is executing failed state in updated transactions. How I can get that purchased details (atleast original receiptID) as we get in Initial transaction.

There is two way to get user purchased transaction details:

1. Refresh receipt
2. Restore completed transaction

To know more about difference between refreshing receipt & restore transaction in details, Please check:- SKReceiptRefreshRequest vs restoreCompletedTransactions

In Simply,

• Refreshing the receipt asks the App Store for the latest copy of the receipt.
• Restoring completed transactions creates a new transaction for every completed transaction the user made, essentially replaying history for your transaction queue observer.

Question: How I can get that purchased details (atleast original receiptID) as we get in Initial transaction.

Answer: If you want to verify user with original receiptID every time each time than user SKReceiptRefreshRequest for validating user transaction.

Note: Anytime if you validating user with RestoreCompletedTransactions, Your transactionID will change. Find list of parameter that change while restoreTransaction: https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ReceiptFields.html#//apple_ref/doc/uid/TP40010573-CH106-SW1