Subscription Groups

From Apple Docs - Offering Subscriptions:

A subscription group is a set of in-app purchases that you can create to provide users with a range of content offerings, service levels, or durations to best meet their needs. Users can only buy one subscription within a subscription group at a time. If users would want to buy more that one type of subscription — for example, to subscribe to more than one channel in a streaming app — you can put these in-app purchases in different subscription groups.

You can verify all subscriptions within the same group with the verifySubscriptions method:

let appleValidator = AppleReceiptValidator(service: .production, sharedSecret: "your-shared-secret")
SwiftyStoreKit.verifyReceipt(using: appleValidator) { result in
    switch result {
    case .success(let receipt):
        let productIds = Set([ "com.musevisions.SwiftyStoreKit.Weekly",
                               "com.musevisions.SwiftyStoreKit.Monthly",
                               "com.musevisions.SwiftyStoreKit.Yearly" ])
        let purchaseResult = SwiftyStoreKit.verifySubscriptions(productIds: productIds, inReceipt: receipt)
        switch purchaseResult {
        case .purchased(let expiryDate, let items):
            print("\(productIds) are valid until \(expiryDate)\n\(items)\n")
        case .expired(let expiryDate, let items):
            print("\(productIds) are expired since \(expiryDate)\n\(items)\n")
        case .notPurchased:
            print("The user has never purchased \(productIds)")
        }
    case .error(let error):
        print("Receipt verification failed: \(error)")
    }
}

Get distinct purchase identifiers

You can retrieve all product identifiers with the getDistinctPurchaseIds method:

let appleValidator = AppleReceiptValidator(service: .production, sharedSecret: "your-shared-secret")
SwiftyStoreKit.verifyReceipt(using: appleValidator) { result in
    switch result {
    case .success(let receipt):
        let productIds = SwiftyStoreKit.getDistinctPurchaseIds(inReceipt: receipt)
        let purchaseResult = SwiftyStoreKit.verifySubscriptions(productIds: productIds, inReceipt: receipt)
        switch purchaseResult {
        case .purchased(let expiryDate, let items):
            print("\(productIds) are valid until \(expiryDate)\n\(items)\n")
        case .expired(let expiryDate, let items):
            print("\(productIds) are expired since \(expiryDate)\n\(items)\n")
        case .notPurchased:
            print("The user has never purchased \(productIds)")
        }
    case .error(let error):
        print("Receipt verification failed: \(error)")
    }
}