Fix Swift 6 sample concurrency issues

platforms/swift/Samples/CheckoutKitSwiftDemo/CheckoutKitSwiftDemo/Sources/Lib/KeychainHelper.swift

@@ -28,7 +28,8 @@ struct OAuthTokenResult: Codable {
     }
 }
 
-final class KeychainHelper: Sendable {
+@MainActor
+final class KeychainHelper {
     static let shared = KeychainHelper()
 
     private let logger = OSLogger(prefix: "Keychain", logLevel: ShopifyCheckoutKit.configuration.logLevel)

platforms/swift/Samples/CheckoutKitSwiftDemo/CheckoutKitSwiftDemo/Sources/Lib/Logger.swift

@@ -1,8 +1,9 @@
 import Foundation
 import ShopifyCheckoutKit
 
-final class FileLogger: Logger {
+final class FileLogger: Logger, @unchecked Sendable {
     private let fileHandle: FileHandle?
+    private let lock = NSLock()
 
     let logFileUrl: URL
 
@@ -24,6 +25,9 @@ final class FileLogger: Logger {
     }
 
     public func log(_ message: String) {
+        lock.lock()
+        defer { lock.unlock() }
+
         guard let fileHandle else {
             print("File handle is nil")
             return
@@ -43,6 +47,9 @@ final class FileLogger: Logger {
     }
 
     public func clearLogs() {
+        lock.lock()
+        defer { lock.unlock() }
+
         do {
             try "".write(toFile: logFileUrl.path, atomically: false, encoding: .utf8)
         } catch let error as NSError {

platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/ShopifyAcceleratedCheckoutsApp/EnvironmentVariables.swift

@@ -8,19 +8,12 @@ public enum EnvironmentVariables {
     }
 
     private static func getKey(for key: String) -> String {
-        guard let value = EnvironmentVariables.infoDictionary[key] as? String else {
+        guard let value = Bundle.main.infoDictionary?[key] as? String else {
             fatalError("Environment variable \(key) must be set in the Storefront.xcconfig file")
         }
         return value
     }
 
-    private static let infoDictionary: [String: Any] = {
-        guard let dict = Bundle.main.infoDictionary else {
-            fatalError("Plist file not found")
-        }
-        return dict
-    }()
-
     public static let storefrontAccessToken: String = getKey(for: Keys.storefrontAccessToken)
 
     public static let storefrontDomain: String = getKey(for: Keys.storefrontDomain)

platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/ShopifyAcceleratedCheckoutsApp/Network.swift

@@ -18,7 +18,8 @@ typealias ProductVariants = Storefront.GetProductsQuery.Data.Products.Node.Varia
 typealias ProductVariant = Storefront.GetProductsQuery.Data.Products.Node.Variants.Node
 typealias ProductPrice = Storefront.GetProductsQuery.Data.Products.Node.Variants.Node.Price
 
-class Network {
+@MainActor
+final class Network {
     static let shared = Network()
 
     /// Get the device's language code mapped to Shopify's LanguageCode enum