SecureTaskSwitcher is rewritten to swift

Example/SMSecureTaskSwitcher/AppDelegate.swift

@@ -14,11 +14,12 @@ import SMSecureTaskSwitcher
 class AppDelegate: UIResponder, UIApplicationDelegate {
 
     var window: UIWindow?
-    var secureTaskSwitcher: SMSecureTaskSwitcher?
+    var secureTaskSwitcher: SecureTaskSwitcher?
 
     func application(_ application: UIApplication,
                      didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
-        secureTaskSwitcher = SMSecureTaskSwitcher()
+        secureTaskSwitcher = SecureTaskSwitcher()
+
         return true
     }
 

SMSecureTaskSwitcher/Classes/SecureTaskSwitcher.swift

@@ -0,0 +1,70 @@
+//
+//  SecureTaskSwitcher.swift
+//  SMSecureTaskSwitcher
+//
+//  Created by Miroslaw Stanek on 25/10/2021.
+//
+
+import Foundation
+import UIKit
+
+public class SecureTaskSwitcher {
+
+    let secureWindow: UIWindow
+    let notificationCenter: NotificationCenter
+    let mainScreen: UIScreen
+    let configuration: SMSecureTaskSwitcherConfiguration
+
+    public init(configuration: SMSecureTaskSwitcherConfiguration = SMSecureTaskSwitcherBlurredConfiguration(),
+         notificationCenter: NotificationCenter = NotificationCenter.default,
+         mainScreen: UIScreen = UIScreen.main) {
+        self.notificationCenter = notificationCenter
+        self.mainScreen = mainScreen
+        self.configuration = configuration
+
+        self.secureWindow = UIWindow.init(frame: self.mainScreen.bounds)
+        self.secureWindow.windowLevel = UIWindow.Level.alert + 10
+        self.secureWindow.backgroundColor = UIColor.clear
+        self.secureWindow.isHidden = true
+
+        self.secureWindow.rootViewController = securedViewController()
+
+        setupObservers()
+    }
+
+    private func securedViewController() -> UIViewController {
+        let rootViewController: UIViewController = UIViewController()
+        rootViewController.view.backgroundColor = UIColor.clear
+        return rootViewController
+    }
+
+    private func setupObservers() {
+        self.notificationCenter.addObserver(self,
+                                            selector: #selector(applicationWillEnterForeground),
+                                            name: UIApplication.willEnterForegroundNotification,
+                                            object: nil)
+    }
+
+    public func applicationDidEnterBackground() {
+        self.updateSecureView()
+        self.secureWindow.isHidden = false
+    }
+
+    @objc
+    public func applicationWillEnterForeground() {
+        self.secureWindow.isHidden = true
+    }
+
+    private func updateSecureView() {
+        if let view = self.secureWindow.rootViewController?.view {
+            for (_, subview) in view.subviews.enumerated() {
+                subview.removeFromSuperview()
+            }
+        }
+
+        self.secureWindow.rootViewController?.view
+            .addSubview(self.configuration.secureView(forFrame: self.mainScreen.bounds))
+    }
+}
+
+