Integrating in-app purchases (IAP) in iOS apps allows you to offer additional content, features, or subscriptions to users within your app. Here’s a basic guide on how to implement in-app purchases in iOS apps:

1. Set Up App in App Store Connect:
   • Log in to your App Store Connect account.
   • Create an App ID for your app.
   • Set up an app record in App Store Connect.
   • Enable in-app purchases for your app.
2. Configure Xcode Project:
   • Enable in-app purchases capabilities for your Xcode project.
   • Add a new capability named “In-App Purchase” in the project settings.
3. Add StoreKit Framework:
   • Import the StoreKit framework into your project.
   • Add import StoreKit to the Swift files where you’ll be working with in-app purchases.
4. Create Products in App Store Connect:
   • Define the products you want to offer as in-app purchases in App Store Connect (e.g., consumable, non-consumable, subscriptions).
   • Set up product pricing and availability.
5. Implement StoreKit in Your App:
   • Set up a StoreKit helper class to handle in-app purchases.
   • Use SKProductsRequest to fetch product information from the App Store.
   • Implement SKPaymentTransactionObserver to handle transaction updates.
6. Present Products to Users:
   • Display the available products to users within your app.
   • Allow users to select and purchase products.
7. Handle Transactions:
   • Process purchased products by implementing the paymentQueue(_:updatedTransactions:) method of the SKPaymentTransactionObserver protocol.
   • Validate receipts and unlock purchased content or features.
8. Test In-App Purchases:
   • Test in-app purchases using sandbox accounts in the App Store sandbox environment.
   • Verify that purchasing, restoring purchases, and handling transactions work as expected.
9. Handle Purchases in Your App:
   • Unlock purchased content or features in your app based on successful transactions.
   • Persist user’s purchases and restore them when necessary.
10. Submit App for Review:
    • Before submitting your app to the App Store, ensure that in-app purchases are working correctly and comply with App Store Review Guidelines.
    • Submit your app for review in App Store Connect.

Here is class you can use to implement features:

import Foundation

enum SubscriptionType {
    case freeTrial
    case monthly
    case yearly
    case weekly
}

class SubscriptionManager {
    static let shared = SubscriptionManager()
    
    private init() {}
    
    func subscribe(type: SubscriptionType) {
        switch type {
        case .freeTrial:
            startFreeTrial()
        case .monthly:
            startMonthlySubscription()
        case .yearly:
            startYearlySubscription()
        case .weekly:
            startWeeklySubscription()
        }
    }
    
    private func startFreeTrial() {
        // Logic for starting the free trial
        print("Free trial started")
    }
    
    private func startMonthlySubscription() {
        // Logic for starting the monthly subscription
        print("Monthly subscription started")
    }
    
    private func startYearlySubscription() {
        // Logic for starting the yearly subscription
        print("Yearly subscription started")
    }
    
    private func startWeeklySubscription() {
        // Logic for starting the weekly subscription
        print("Weekly subscription started")
    }
    
    func checkSubscriptionStatus() -> SubscriptionType? {
        // Logic to check the subscription status and return the type of subscription
        // For example, check if the user has an active subscription
        // Return the subscription type if active, otherwise return nil
        return .monthly // Example, change this based on actual logic
    }
}

In this singleton class:

• SubscriptionManager is a singleton class responsible for managing subscription options.
• It has private initializers to prevent the creation of multiple instances.
• The subscribe method allows users to subscribe to different types of subscriptions (free trial, monthly, yearly, weekly).
• The checkSubscriptionStatus method checks the subscription status and returns the type of subscription the user has.
• Private methods (startFreeTrial, startMonthlySubscription, startYearlySubscription, startWeeklySubscription) contain the logic for starting each type of subscription.

You can use the SubscriptionManager singleton class to manage subscriptions and check the subscription status in your app. Here’s how you can use it in your app:

// Subscribe to a monthly subscription
SubscriptionManager.shared.subscribe(type: .monthly)

// Check the subscription status
if let subscriptionType = SubscriptionManager.shared.checkSubscriptionStatus() {
    switch subscriptionType {
    case .freeTrial:
        print("User has a free trial subscription")
    case .monthly:
        print("User has a monthly subscription")
    case .yearly:
        print("User has a yearly subscription")
    case .weekly:
        print("User has a weekly subscription")
    }
} else {
    print("User does not have an active subscription")
}