implement functionality

Author: Nikita Mikheev

Package.swift

@@ -9,7 +9,8 @@ let package = Package(
         // Products define the executables and libraries a package produces, and make them visible to other packages.
         .library(
             name: "WindowInstanceManager",
-            targets: ["WindowInstanceManager"]),
+            targets: ["WindowInstanceManager"]
+        ),
     ],
     dependencies: [
         // Dependencies declare other packages that this package depends on.
@@ -20,9 +21,7 @@ let package = Package(
         // Targets can depend on other targets in this package, and on products in packages this package depends on.
         .target(
             name: "WindowInstanceManager",
-            dependencies: []),
-        .testTarget(
-            name: "WindowInstanceManagerTests",
-            dependencies: ["WindowInstanceManager"]),
+            dependencies: []
+        )
     ]
 )

README.md

@@ -1,3 +1,3 @@
 # WindowInstanceManager
 
-A description of this package.
+`WindowInstanceManager` is an utility wich helps to manage multiple windows for a single app.

Sources/WindowInstanceManager/Entities/Window.swift

@@ -0,0 +1,43 @@
+//
+//  Window.swift
+//  Created by Nikita Mikheev on 26.02.2022.
+//
+
+import UIKit
+
+protocol WindowDelegate: AnyObject {
+    func close(window: Window)
+}
+
+final class Window {
+    // MARK: Delegate
+    weak var delegate: WindowDelegate?
+    
+    // MARK: Properties
+    let id = UUID()
+    
+    private(set) var uiWindow: UIWindow?
+    private(set) weak var resignedKeyWidnow: UIWindow!
+    
+    // MARK: Initializers
+    init(
+        application: UIApplication,
+        rootController: UIViewController
+    ) {
+        guard let applicationWidnow = application.keyWindow else {
+            assertionFailure("Application does not have a keyWindow!")
+            return
+        }
+        resignedKeyWidnow = applicationWidnow
+        
+        uiWindow = UIWindow(frame: UIScreen.main.bounds)
+        uiWindow!.rootViewController = rootController
+    }
+}
+
+// MARK: - WindowControlInterface
+extension Window: WindowControlInterface {
+    func close() {
+        delegate?.close(window: self)
+    }
+}

Sources/WindowInstanceManager/WindowInstanceManager.swift

@@ -1,6 +1,71 @@
-public struct WindowInstanceManager {
-    public private(set) var text = "Hello, World!"
+import UIKit
 
-    public init() {
+public protocol WindowControlInterface {
+    var uiWindow: UIWindow? { get }
+    func close()
+}
+
+public protocol WindowInstanceManaging {
+    func presentNew(withRoot controller: UIViewController) -> WindowControlInterface
+}
+
+public final class WindowInstanceManager {
+    // MARK: Singleton
+    public static func shared(for application: UIApplication) -> WindowInstanceManaging {
+        guard let instance = instance else {
+            instance = WindowInstanceManager(application: application)
+            return instance!
+        }
+        
+        return instance
+    }
+    private static var instance: WindowInstanceManager?
+    
+    // MARK: Properties
+    private let application: UIApplication
+    private var instances = [UUID: Window]()
+    
+    // MARK: Initializers
+    private init(
+        application: UIApplication
+    ) {
+        self.application = application
+    }
+}
+
+// MARK: - WindowInstanceManaging
+extension WindowInstanceManager: WindowInstanceManaging {
+    public func presentNew(withRoot controller: UIViewController) -> WindowControlInterface {
+        let window = Window(
+            application: application,
+            rootController: controller
+        )
+        
+        instances[window.id] = window
+        window.delegate = self
+        
+        window.uiWindow?.makeKeyAndVisible()
+        
+        return window
+    }
+}
+
+// MARK: - WindowDelegate
+extension WindowInstanceManager: WindowDelegate {
+    func close(window: Window) {
+        guard let uiWindow = window.uiWindow else {
+            return
+        }
+        
+        if let resigned = window.resignedKeyWidnow {
+            resigned.makeKeyAndVisible()
+        } else {
+            application.windows.last?.makeKeyAndVisible()
+        }
+        
+        uiWindow.resignKey()
+        uiWindow.isHidden = true
+        
+        instances[window.id] = nil
     }
 }