Update MigrationGuideSwift6.swift

Author: janeshsutharios

SwiftUIExamples/MigrationGuideSwift6.swift

@@ -3,21 +3,19 @@ Prefer Value Types (Structs) When Possible
 Value types are copied when passed around, reducing the risk of shared mutable state.
 
 // MARK: Example 1 
-/*class HomeViewController {
-
-     private var loadingView = UIView() // Error here `Main actor-isolated default value in a nonisolated context`
+class HomeViewControllerLegacy {
 
+    private var loadingView = UIView() // Error here `Main actor-isolated default value in a nonisolated context`
     var hasLaunched = false
 
     @MainActor
      func home() {
         self.hasLaunched = true
     }
 }
-*/
-// To solve it - initializing the view at declaration time, so you can safely create it in viewDidLoad() which runs on the main thread.
 
-class HomeViewController: UIViewController {
+// To solve it - initializing the view at declaration time, so you can safely create it in viewDidLoad() which runs on the main thread.
+class HomeViewControllerNew: UIViewController {
     private var loadingView: UIView!
 
     override func viewDidLoad() {
@@ -29,15 +27,14 @@ class HomeViewController: UIViewController {
 }
 
 // MARK: Example 2 Passing closure as a 'sending' parameter risks causing data races 
-/*
-class Logger {
+class LoggerLegacy {
     var logs: [String] = []
 
     func log(_ message: String) {
         logs.append(message)
     }
 }
-struct Worker {
+struct WorkerLegacy {
     let logger: Logger
 
     func doWork() {
@@ -46,21 +43,21 @@ struct Worker {
         }
     }
 }
-*/
+
 //-> If you know there is no data race in your codebase & want to skip data race use @preconcurrency
 @preconcurrency
-class Logger {
+class LoggerNew {
     var logs: [String] = []
 
     func log(_ message: String) {
         logs.append(message)
     }
 }
 
-extension Logger: @unchecked Sendable {}
+extension LoggerNew: @unchecked Sendable {}
 
-struct Worker {
-    let logger: Logger
+struct WorkerNew {
+    let logger: LoggerNew
 
     func doWork() {
         Task {
@@ -70,8 +67,8 @@ struct Worker {
 }
 
 // MARK: Example # Trying to access heightConstraint from background thread.
-/*
-class ProfileViewController: UIViewController {
+
+class ProfileViewControllerLegacy: UIViewController {
     var heightConstraint: NSLayoutConstraint!
 
     override func viewDidLoad() {
@@ -85,9 +82,9 @@ class ProfileViewController: UIViewController {
         }
     }
 }
-*/
+
 // Solution ->
-class ProfileViewController: UIViewController {
+class ProfileViewControllerNew: UIViewController {
     var heightConstraint: NSLayoutConstraint!
 
     override func viewDidLoad() {
@@ -110,7 +107,7 @@ class CartView {
     @IBOutlet var label: UILabel!
 
      // Error version
-    func addItem() {
+    func addItemLegacy() {
         DispatchQueue.global().async {
             // Error here # Main actor-isolated property 'text' can not be mutated from a Sendable closure
             self.label.text = "Updated"
@@ -127,7 +124,7 @@ class CartView {
 }
 
 // MARK: Example #5 Accessing Non-Sendable Types Across Threads
-class SongClass {
+class SongClassLegacy {
     var data: String = ""
 
     func update() {
@@ -139,7 +136,7 @@ class SongClass {
     }
 }
 
-actor SongClassFixed {
+actor SongClassNew {
     private var data = ""
 
     func append(_ value: String) {
@@ -151,5 +148,47 @@ actor SongClassFixed {
     }
 }
 
+// MARK: Example #6 sendable examples
+final class SteelFactoryLegacy {
+    // Closure to be called after background work
+    var onUpdate: (() -> Void)?
+    
+    func performWork() {
+        DispatchQueue.global().async { [weak self] in
+            // Simulate background work
+            sleep(1)
+            // Warning Capture of 'self' with non-sendable type 'SteelFactoryLegacy?' in a '@Sendable' closure
+            self?.onUpdate?()
+            
+        }
+    }
+}
+
+
+final class SteelFactoryNew {
+    // Closure that can be safely called from concurrent contexts
+    var onUpdate: (@Sendable () -> Void)?
+
+    func performWork() {
+        DispatchQueue.global().async { [onUpdate] in
+            // Simulate background work
+            sleep(1)
 
+            // Safely call the closure
+            onUpdate?()
+        }
+    }
+}
+// Usage -
+class CompanyOffice {
+    
+    func getInfo() {
+        let manager = SteelFactoryNew()
+        manager.onUpdate = { [message = "Update received!"] in
+            print(message)
+        }
+        manager.performWork()
+
+    }
+}