Add StoreKit utils

README.md

@@ -34,6 +34,7 @@ SwiftKit is divided into the following sections:
 * Messaging
 * Network
 * Services
+* StoreKit
 * Validation
 
 You can explore the various sections in the documentation or in the demo app.

Release Notes.md

@@ -3,11 +3,11 @@
 
 ## 1.0
 
-After a lot of waiting and stabilizing, I think it's time to push the major release button.
+After a lot of waiting and stabilizing, I think it's time to push the major release button.  
 
-There are no drastic changes, but I use this in most of my projects and find it very helpful and stable.  
+This version drastically improves documentation and ships with a DocC documentation archive.
 
-This version drastically improves documentation and ships with a DocC documentation archive. 
+This version also introduces a new `StoreKit` namespace with handy utils for managing StoreKit products and purchases.  
 
 ### ✨ New features
 
@@ -15,6 +15,10 @@ This version drastically improves documentation and ships with a DocC documentat
 * `Date` has a new `components` extension for retrieving year, month, hour etc.
 * `String` has new `boolValue` extension.
 
+* `StoreService` is a new protocol for managing StoreKit products and purchases.
+* `StoreContext` is a new class for managing StoreKit products and purchases.
+* `StandardStoreService` is a new class that implements the `StoreService` protocol.
+
 
 ## 0.7.0
 

Sources/SwiftKit/Data/Persisted.swift

@@ -0,0 +1,46 @@
+//
+//  Persisted.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2020-04-05.
+//  Copyright © 2020 Daniel Saidi. All rights reserved.
+//
+
+import Foundation
+
+/**
+ This property wrapper automatically persists any new values
+ to user defaults and sets the initial property value to the
+ last persisted value or a fallback value.
+ 
+ This type is internal, since the `SwiftUI` instance is used
+ to greated extent.
+ */
+@propertyWrapper
+struct Persisted<T: Codable> {
+    
+    init(
+        key: String,
+        store: UserDefaults = .standard,
+        defaultValue: T) {
+        self.key = key
+        self.store = store
+        self.defaultValue = defaultValue
+    }
+    
+    private let key: String
+    private let store: UserDefaults
+    private let defaultValue: T
+
+    var wrappedValue: T {
+        get {
+            guard let data = store.object(forKey: key) as? Data else { return defaultValue }
+            let value = try? JSONDecoder().decode(T.self, from: data)
+            return value ?? defaultValue
+        }
+        set {
+            let data = try? JSONEncoder().encode(newValue)
+            store.set(data, forKey: key)
+        }
+    }
+}

Sources/SwiftKit/StoreKit/StandardStoreService.swift

@@ -0,0 +1,168 @@
+//
+//  StandardStoreService.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-08.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import StoreKit
+
+/**
+ This service class implements `StoreService` by integrating
+ with StoreKit.
+ 
+ The service keeps products and purchases in sync, using the
+ provided ``StoreContext``. An app can listen to any changes
+ in the context to drive UI changes.
+ 
+ You can configure a test app to use this service with local
+ products by adding a StoreKit configuration file to the app.
+ */
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+public class StandardStoreService: StoreService {
+    
+    /**
+     Create a service instance for the provided `productIds`,
+     that syncs any changes to the provided `context`.
+     
+     - Parameters:
+       - productIds: The IDs of the products to handle.
+       - context: The store context to sync with.
+     */
+    public init(
+        productIds: [String],
+        context: StoreContext = StoreContext()) {
+        self.productIds = productIds
+        self.storeContext = context
+        self.transactionTask = nil
+        self.transactionTask = getTransactionListenerTask()
+    }
+    
+    deinit {
+        self.transactionTask = nil
+    }
+    
+    private let productIds: [String]
+    private let storeContext: StoreContext
+    private var transactionTask: Task<Void, Error>?
+    
+    /**
+     Get all available products.
+     */
+    public func getProducts() async throws -> [Product] {
+        try await Product.products(for: productIds)
+    }
+    
+    /**
+     Purchase a certain product.
+     */
+    public func purchase(_ product: Product) async throws -> Product.PurchaseResult {
+        let result = try await product.purchase()
+        switch result {
+        case .success(let result): try await handleTransaction(result)
+        case .pending: break
+        case .userCancelled: break
+        @unknown default: break
+        }
+        return result
+    }
+    
+    /**
+     Restore purchases that are not on this device.
+     */
+    public func restorePurchases() async throws {
+        try await syncTransactions()
+    }
+
+    /**
+     Sync product and purchase information from the store to
+     the provided store context.
+     */
+    public func syncStoreData() async throws {
+        let products = try await getProducts()
+        await updateContext(with: products)
+        try await restorePurchases()
+    }
+}
+
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+private extension StandardStoreService {
+    
+    /**
+     Create a task that can be used to listen for and acting
+     on transaction changes.
+     */
+    func getTransactionListenerTask() -> Task<Void, Error> {
+        Task.detached {
+            for await result in Transaction.updates {
+                do {
+                    try await self.handleTransaction(result)
+                } catch {
+                    print("Transaction listener error: \(error)")
+                }
+            }
+        }
+    }
+    
+    /**
+     Try resolving a valid transaction for a certain product.
+     */
+    func getValidTransaction(for productId: String) async throws -> Transaction? {
+        guard let latest = await Transaction.latest(for: productId) else { return nil }
+        let result = try verifyTransaction(latest)
+        return result.isValid ? result : nil
+    }
+    
+    /**
+     Handle the transaction in the provided `result`.
+     */
+    func handleTransaction(_ result: VerificationResult<Transaction>) async throws {
+        let transaction = try verifyTransaction(result)
+        await updateContext(with: transaction)
+        await transaction.finish()
+    }
+    
+    /**
+     Sync the transactions of all available products.
+     */
+    func syncTransactions() async throws {
+        var transactions: [Transaction] = []
+        for id in productIds {
+            if let transaction = try await getValidTransaction(for: id) {
+                transactions.append(transaction)
+            }
+        }
+        await updateContext(with: transactions)
+    }
+    
+    /**
+     Verify the transaction in the provided `result`
+     */
+    func verifyTransaction(_ result: VerificationResult<Transaction>) throws -> Transaction {
+        switch result {
+        case .unverified(let transaction, let error): throw StoreServiceError.invalidTransaction(transaction, error)
+        case .verified(let transaction): return transaction
+        }
+    }
+}
+
+@MainActor
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+private extension StandardStoreService {
+    
+    func updateContext(with products: [Product]) {
+        storeContext.products = products
+    }
+    
+    func updateContext(with transaction: Transaction) {
+        var transactions = storeContext.transactions
+            .filter { $0.productID != transaction.productID }
+        transactions.append(transaction)
+        storeContext.transactions = transactions
+    }
+    
+    func updateContext(with transactions: [Transaction]) {
+        storeContext.transactions = transactions
+    }
+}

Sources/SwiftKit/StoreKit/StoreContext+Products.swift

@@ -0,0 +1,27 @@
+//
+//  StoreContext+Products.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-09.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import StoreKit
+
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+public extension StoreContext {
+    
+    /**
+     Whether or not a certain product has an active purchase.
+     */
+    func isProductPurchased(id: String) -> Bool {
+        purchasedProductIds.contains(id)
+    }
+    
+    /**
+     Whether or not a certain product has an active purchase.
+     */
+    func isProductPurchased(_ product: Product) -> Bool {
+        isProductPurchased(id: product.id)
+    }
+}

Sources/SwiftKit/StoreKit/StoreContext.swift

@@ -0,0 +1,92 @@
+//
+//  StoreContext.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-08.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import StoreKit
+import Combine
+
+/**
+ This class can be used to manage store information in a way
+ that makes it observable.
+ 
+ Since the `Product` type isn't `Codable`, `products` is not
+ permanently persisted, which means that this information is
+ reset if the app restarts. Due to this, any changes to this
+ property will also update `productIds`, which gives you the
+ option to map the IDs to a local product representation and
+ present previously fetched products.
+ 
+ Note however that a `Product` instance is needed to perform
+ a purchase.
+ */
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+public class StoreContext: ObservableObject {
+    
+    public init() {
+        productIds = persistedProductIds
+        purchasedProductIds = persistedPurchasedProductIds
+    }
+    
+    /**
+     The available products.
+     
+     Since `Product` isn't `Codable`, this property can't be
+     persisted. It must be re-fetched when the app starts.
+     */
+    public var products: [Product] = [] {
+        didSet { productIds = products.map { $0.id} }
+    }
+    
+    /**
+     The available products IDs.
+     
+     This list is permanently persisted and can be mapped to
+     a local product representation to present temp. product
+     info before `products` have been re-fetched.
+     */
+    @Published
+    public private(set) var productIds: [String] = [] {
+        willSet { persistedProductIds = newValue }
+    }
+    
+    /**
+     The purchased products IDs.
+     
+     This list is permanently persisted and can be mapped to
+     a local product representation to present temp. product
+     info before `transactions` have been re-fetched.
+     */
+    @Published
+    public private(set) var purchasedProductIds: [String] = [] {
+        willSet { persistedPurchasedProductIds = newValue }
+    }
+    
+    /**
+     The active transactions.
+     
+     Since `Transaction` isn't `Codable` this property can't
+     be persisted. It must be re-fetched when the app starts.
+     */
+    public var transactions: [StoreKit.Transaction] = [] {
+        didSet { purchasedProductIds = transactions.map { $0.productID } }
+    }
+    
+    
+    // MARK: - Persisted Properties
+    
+    @Persisted(key: key("productIds"), defaultValue: [])
+    private var persistedProductIds: [String]
+    
+    @Persisted(key: key("purchasedProductIds"), defaultValue: [])
+    private var persistedPurchasedProductIds: [String]
+}
+
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+private extension StoreContext {
+    
+    static func key(_ name: String) -> String { "store.\(name)" }
+}

Sources/SwiftKit/StoreKit/StoreService.swift

@@ -0,0 +1,38 @@
+//
+//  StoreService.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-08.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import StoreKit
+
+/**
+ This protocol can be implemented by any classes that can be
+ used to manage store products.
+ */
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+public protocol StoreService {
+    
+    /**
+     Get all available products.
+     */
+    func getProducts() async throws -> [Product]
+    
+    /**
+     Purchase a certain product.
+     */
+    func purchase(_ product: Product) async throws -> Product.PurchaseResult
+    
+    /**
+     Restore purchases that are not on this device.
+     */
+    func restorePurchases() async throws
+    
+    /**
+     Sync product and purchase information from the store to
+     any implementation defined sync destination.
+     */
+    func syncStoreData() async throws
+}

Sources/SwiftKit/StoreKit/StoreServiceError.swift

@@ -0,0 +1,20 @@
+//
+//  StoreServiceError.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-08.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import Foundation
+import StoreKit
+
+/**
+ This enum lists errors that can be thrown by store services.
+ */
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+public enum StoreServiceError: Error {
+    
+    /// This is thrown if a transaction can't be verified.
+    case invalidTransaction(Transaction, VerificationResult<Transaction>.VerificationError)
+}

Sources/SwiftKit/StoreKit/Transaction+Valid.swift

@@ -0,0 +1,25 @@
+//
+//  Transaction+Valid.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-08.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import StoreKit
+
+@available(iOS 15.0, macOS 12.0, watchOS 8.0, tvOS 15.0, *)
+extension Transaction {
+    
+    /**
+     Whether or not the transaction is valid.
+     
+     The logic may have to be adjusted as more product types
+     are handled with this service.
+     */
+    var isValid: Bool {
+        if revocationDate != nil { return false }
+        guard let date = expirationDate else { return false }
+        return date > Date()
+    }
+}

Sources/SwiftKit/SwiftKit.docc/SwiftKit.md

@@ -130,6 +130,13 @@ This namespace contains composer extensions.
 - ``MultiProxy``
 - ``Proxy``
 
+### StoreKit
+
+- ``StoreService``
+- ``StoreContext``
+- ``StoreServiceError``
+- ``StandardStoreService``
+
 ### Validation
 
 - ``EmailValidator``

Tests/SwiftKitTests/Extensions/String/String+BoolTests.swift

@@ -0,0 +1,38 @@
+//
+//  String+BoolTests.swift
+//  SwiftKit
+//
+//  Created by Daniel Saidi on 2021-11-02.
+//  Copyright © 2021 Daniel Saidi. All rights reserved.
+//
+
+import Quick
+import Nimble
+import SwiftKit
+
+class String_BoolTests: QuickSpec {
+    
+    override func spec() {
+        
+        describe("bool value") {
+            
+            func result(for string: String) -> Bool {
+                string.boolValue
+            }
+            
+            it("is valid for many different true expressions") {
+                let expected = ["YES", "yes", "1"]
+                expected.forEach {
+                    expect(result(for: $0)).to(beTrue())
+                }
+            }
+            
+            it("is valid for many different false expressions") {
+                let expected = ["NO", "no", "0"]
+                expected.forEach {
+                    expect(result(for: $0)).to(beFalse())
+                }
+            }
+        }
+    }
+}