Merge pull request #2248 from woocommerce/issue/2173-kfo-struct-to-class

Convert KeyboardFrameObserver to class

Author: shiki

WooCommerce/Classes/ViewRelated/Keyboard/KeyboardFrameObserver.swift

@@ -1,7 +1,7 @@
 import UIKit
 
 /// Observes the keyboard frame and notifies its subscriber.
-struct KeyboardFrameObserver {
+final class KeyboardFrameObserver {
     private let onKeyboardFrameUpdate: OnKeyboardFrameUpdate
 
     /// Provides the last known keyboard state.
@@ -36,19 +36,16 @@ struct KeyboardFrameObserver {
     ///
     /// - Parameter sendInitialEvent: If true, the subscriber will be immediately notified
     ///                               using the last known keyboard frame.
-    mutating func startObservingKeyboardFrame(sendInitialEvent: Bool = false) {
-        var observer = self
-        notificationCenter.addObserver(forName: UIResponder.keyboardWillShowNotification,
-                                       object: nil,
-                                       queue: nil) { notification in
-                                        observer.keyboardWillShow(notification)
-        }
+    func startObservingKeyboardFrame(sendInitialEvent: Bool = false) {
+        notificationCenter.addObserver(self,
+                                       selector: #selector(keyboardWillShow(_:)),
+                                       name: UIResponder.keyboardWillShowNotification,
+                                       object: nil)
 
-        notificationCenter.addObserver(forName: UIResponder.keyboardWillHideNotification,
-                                       object: nil,
-                                       queue: nil) { notification in
-                                        observer.keyboardWillHide(notification)
-        }
+        notificationCenter.addObserver(self,
+                                       selector: #selector(keyboardWillHide(_:)),
+                                       name: UIResponder.keyboardWillHideNotification,
+                                       object: nil)
 
         if sendInitialEvent {
             keyboardFrame = keyboardStateProvider.state.frameEnd
@@ -57,14 +54,14 @@ struct KeyboardFrameObserver {
 }
 
 private extension KeyboardFrameObserver {
-    mutating func keyboardWillShow(_ notification: Foundation.Notification) {
+    @objc func keyboardWillShow(_ notification: Foundation.Notification) {
         guard let keyboardFrame = keyboardRect(from: notification) else {
             return
         }
         self.keyboardFrame = keyboardFrame
     }
 
-    mutating func keyboardWillHide(_ notification: Foundation.Notification) {
+    @objc func keyboardWillHide(_ notification: Foundation.Notification) {
         self.keyboardFrame = .zero
     }
 }

WooCommerce/WooCommerceTests/ViewRelated/Keyboard/KeyboardFrameObserverTests.swift

@@ -16,7 +16,7 @@ final class KeyboardFrameObserverTests: XCTestCase {
 
         var actualFrames = [CGRect]()
 
-        var keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
+        let keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
             actualFrames.append(keyboardFrame)
             if actualFrames.count >= expectedFrames.count {
                 XCTAssertEqual(actualFrames, expectedFrames)
@@ -47,7 +47,7 @@ final class KeyboardFrameObserverTests: XCTestCase {
 
         var actualFrames = [CGRect]()
 
-        var keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
+        let keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
             actualFrames.append(keyboardFrame)
             if actualFrames.count >= expectedFrames.count {
                 XCTAssertEqual(actualFrames, expectedFrames)
@@ -70,7 +70,7 @@ final class KeyboardFrameObserverTests: XCTestCase {
 
         let expectationForKeyboardFrame = expectation(description: "Wait for keyboard frame updates")
 
-        var keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
+        let keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
             expectationForKeyboardFrame.fulfill()
         }
         keyboardFrameObserver.startObservingKeyboardFrame()
@@ -88,7 +88,7 @@ final class KeyboardFrameObserverTests: XCTestCase {
 
         let expectationForKeyboardFrame = expectation(description: "Wait for keyboard frame updates")
 
-        var keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
+        let keyboardFrameObserver = KeyboardFrameObserver(notificationCenter: notificationCenter) { (keyboardFrame: CGRect) in
             expectationForKeyboardFrame.fulfill()
         }
         keyboardFrameObserver.startObservingKeyboardFrame()
@@ -101,6 +101,31 @@ final class KeyboardFrameObserverTests: XCTestCase {
         waitForExpectations(timeout: 0.1)
     }
 
+    func testItWillNotEmitNewEventsWhenItIsDeallocated() {
+        // Arrange
+        let notificationCenter = NotificationCenter()
+
+        var eventsLogged = 0
+        var keyboardFrameObserver: KeyboardFrameObserver? = KeyboardFrameObserver(notificationCenter: notificationCenter) { _ in
+            eventsLogged += 1
+        }
+
+        keyboardFrameObserver?.startObservingKeyboardFrame()
+
+        // These should be logged
+        notificationCenter.postKeyboardWillShowNotification(keyboardFrame: CGRect(x: 1, y: 1, width: 1, height: 1))
+        notificationCenter.postKeyboardWillShowNotification(keyboardFrame: CGRect(x: 2, y: 2, width: 2, height: 2))
+
+        // Act
+        keyboardFrameObserver = nil
+
+        // This should not be logged anymore
+        notificationCenter.postKeyboardWillShowNotification(keyboardFrame: CGRect(x: 3, y: 3, width: 3, height: 3))
+
+        // Assert
+        XCTAssertEqual(eventsLogged, 2)
+    }
+
     func testItCanSendInitialEvents() {
         // Arrange
         let expectedKeyboardState = KeyboardState(
@@ -110,7 +135,7 @@ final class KeyboardFrameObserverTests: XCTestCase {
         let keyboardStateProvider = MockKeyboardStateProvider(state: expectedKeyboardState)
 
         var actualKeyboardFrame: CGRect = .zero
-        var keyboardFrameObserver = KeyboardFrameObserver(keyboardStateProvider: keyboardStateProvider) { frame in
+        let keyboardFrameObserver = KeyboardFrameObserver(keyboardStateProvider: keyboardStateProvider) { frame in
             actualKeyboardFrame = frame
         }