Include the transaction with PaymentState.restored

[swoolcock]

Helps with #26 but not a complete solution, as the product IDs are not returned in the restore handler. Rather, you would switch on the payment state in the fallback handler.

InAppPurchase.default.addTransactionObserver(fallbackHandler: { result in
    switch result {
    case .success(let state):
        switch state {
        case .purchased(let transaction), .restored(let transaction):
            // update the local cache (UserDefaults, keychain, etc.)
        // ...
        }
    // ...
    }
})

InAppPurchase.default.restore()

[jinSasaki]

Please use after 2.5.0 version! You can get the transaction when restored by PaymentResponse.transaction :)