Update README, add purchase restoring functionality

README.md

@@ -6,10 +6,48 @@
 
 [![License](https://img.shields.io/badge/license-MIT-blue.svg?style=flat)](http://mit-license.org)
 [![Platform](http://img.shields.io/badge/platform-iOS%20%7C%20macOS%20%7C%20tvOS%20%7C%20watchOS-lightgrey.svg?style=flat)](https://developer.apple.com/resources/)
-[![Language](https://img.shields.io/badge/swift-5.0-orange.svg)](https://developer.apple.com/swift)
+[![Language](https://img.shields.io/badge/swift-5.5-orange.svg)](https://developer.apple.com/swift)
 
 Mercato is a lightweight In-App Purchases (StoreKit 2) library for iOS, tvOS, watchOS, macOS, and Mac Catalyst.
 
+Installation
+------------
+
+### Swift Package Manager
+
+To integrate using Apple's Swift package manager, add the following as a dependency to your `Package.swift`:
+
+```swift
+.package(url: "https://github.com/tikhop/Mercato.git", .upToNextMajor(from: "0.0.1"))
+```
+
+Then, specify `"Mercato"` as a dependency of the Target in which you wish to use Mercato.
+
+Lastly, run the following command:
+```swift
+swift package update
+```
+
+### CocoaPods
+
+In progress...
+
+Then, run the following command:
+
+```bash
+$ pod install
+```
+
+In any swift file you'd like to use Mercato, import the framework with `import Mercato`.
+
+### Requirements
+
+- iOS 15.0 / OSX 12.0 / watchOS 8.0
+- Swift 5.5
+
+Usage
+-------------
+
 ## Essential Reading
 * [Apple - Meet StoreKit 2](https://developer.apple.com/videos/play/wwdc2021/10114/)
 * [Apple - In-App Purchase](https://developer.apple.com/documentation/storekit/in-app_purchase)

Sources/Mercato/Mercato+StoreKit.swift

@@ -0,0 +1,30 @@
+//
+//  File.swift
+//  
+//
+//  Created by Pavel Tikhonenko on 10.10.2021.
+//
+
+import Foundation
+import StoreKit
+
+typealias RenewalState = Product.SubscriptionInfo.RenewalState
+
+public extension Product
+{
+	var isEligibleForIntroOffer: Bool
+	{
+		get async
+		{
+			await subscription?.isEligibleForIntroOffer ?? false
+		}
+	}
+
+	var hasActiveSubscription: Bool
+	{
+		get async
+		{
+			await (try? subscription?.status.first?.state == RenewalState.subscribed) ?? false
+		}
+	}
+}

Sources/Mercato/Mercato.swift

@@ -118,6 +118,11 @@ extension Mercato
 	{
 		await shared.beginRefundProcess(for: productID, in: scene)
 	}
+
+	public static func restorePurchases() async throws
+	{
+		try await AppStore.sync()
+	}
 }
 
 func checkVerified<T>(_ result: VerificationResult<T>) throws -> T

Sources/Mercato/ProductService.swift

@@ -17,7 +17,9 @@ class ProductService
 	{
 		do
 		{
-			return try await Product.products(for: productIds)
+			let products = try await Product.products(for: productIds)
+			cachedProducts = products
+			return products
 		}catch{
 			throw MercatoError.storeKit(error: error as! StoreKitError)
 		}
@@ -36,12 +38,6 @@ class ProductService
 		}
 
 		let transaction = try checkVerified(result)
-
-		//Ignore revoked transactions, they're no longer purchased.
-
-		//For subscriptions, a user can upgrade in the middle of their subscription period. The lower service
-		//tier will then have the `isUpgraded` flag set and there will be a new transaction for the higher service
-		//tier. Ignore the lower service tier transactions which have been upgraded.
 		return transaction.revocationDate == nil && !transaction.isUpgraded
 	}
 }