fix: Use DiscountOfferInputIOS for subscription offers

Changed from SubscriptionOfferIOS to DiscountOfferInputIOS which is
the correct type for promotional offers in subscription requests.

Author: hyochan

Sources/OpenIapModule+ObjC.swift

@@ -146,13 +146,18 @@ import StoreKit
         Task {
             do {
                 // For subscription request, type must be .subs
-                let subscriptionOffer: SubscriptionOfferIOS? = if let offer = offer {
-                    SubscriptionOfferIOS(
-                        id: offer["id"] as? String,
-                        keyIdentifier: offer["keyIdentifier"] as? String,
-                        nonce: (offer["nonce"] as? String).flatMap { UUID(uuidString: $0) },
-                        signature: offer["signature"] as? String,
-                        timestamp: offer["timestamp"] as? Int64 ?? 0
+                let discountOffer: DiscountOfferInputIOS? = if let offer = offer,
+                    let identifier = offer["identifier"] as? String,
+                    let keyIdentifier = offer["keyIdentifier"] as? String,
+                    let nonce = offer["nonce"] as? String,
+                    let signature = offer["signature"] as? String,
+                    let timestamp = offer["timestamp"] as? Double {
+                    DiscountOfferInputIOS(
+                        identifier: identifier,
+                        keyIdentifier: keyIdentifier,
+                        nonce: nonce,
+                        signature: signature,
+                        timestamp: timestamp
                     )
                 } else {
                     nil
@@ -162,7 +167,7 @@ import StoreKit
                     andDangerouslyFinishTransactionAutomatically: nil,
                     appAccountToken: nil,
                     sku: sku,
-                    withOffer: subscriptionOffer
+                    withOffer: discountOffer
                 )
                 let props = RequestPurchaseProps(
                     request: .subscription(