Remove notification observers for NUXViewControllerBase

NUXViewControllerBase is implemented as a protocol. In order not to change architecture using Obj-C runtime feature to create observers and deinitialize them on deinit

Author: staskus

WordPressAuthenticator/NUX/NUXTableViewController.swift

@@ -23,6 +23,10 @@ open class NUXTableViewController: UITableViewController, NUXViewControllerBase,
         setupHelpButtonIfNeeded()
         setupCancelButtonIfNeeded()
     }
+    
+    deinit {
+        removeNotificationObservers()
+    }
 
     public func shouldShowCancelButton() -> Bool {
         return shouldShowCancelButtonBase()

WordPressAuthenticator/NUX/NUXViewController.swift

@@ -27,6 +27,10 @@ open class NUXViewController: UIViewController, NUXViewControllerBase, UIViewCon
         setupCancelButtonIfNeeded()
         setupBackgroundTapGestureRecognizer()
     }
+    
+    deinit {
+        removeNotificationObservers()
+    }
 
     // properties specific to NUXViewController
     @IBOutlet var submitButton: NUXButton?

WordPressAuthenticator/NUX/NUXViewControllerBase.swift

@@ -286,14 +286,46 @@ extension NUXViewControllerBase where Self: UIViewController, Self: UIViewContro
     private func setupNotificationsIndicator() {
         helpNotificationIndicator.isHidden = true
 
-        NotificationCenter.default.addObserver(forName: .wordpressSupportNotificationReceived, object: nil, queue: nil) { [weak self] _ in
+        wordpressSupportNotificationReceivedObserver = NotificationCenter.default.addObserver(forName: .wordpressSupportNotificationReceived, object: nil, queue: nil) { [weak self] _ in
             self?.refreshSupportNotificationIndicator()
         }
-        NotificationCenter.default.addObserver(forName: .wordpressSupportNotificationCleared, object: nil, queue: nil) { [weak self] _ in
+        wordpressSupportNotificationClearedObserver = NotificationCenter.default.addObserver(forName: .wordpressSupportNotificationCleared, object: nil, queue: nil) { [weak self] _ in
             self?.refreshSupportNotificationIndicator()
         }
     }
 
+    private var wordpressSupportNotificationReceivedObserver: NSObjectProtocol? {
+        get {
+            
+            objc_getAssociatedObject(self, &wordpressSupportNotificationReceivedKey) as? NSObjectProtocol
+        }
+        set {
+            objc_setAssociatedObject(self, &wordpressSupportNotificationReceivedKey, newValue, .OBJC_ASSOCIATION_RETAIN)
+        }
+    }
+
+    private var wordpressSupportNotificationClearedObserver: NSObjectProtocol? {
+        get {
+            objc_getAssociatedObject(self, &wordpressSupportNotificationClearedKey) as? NSObjectProtocol
+        }
+        set {
+            objc_setAssociatedObject(self, &wordpressSupportNotificationClearedKey, newValue, .OBJC_ASSOCIATION_RETAIN)
+        }
+    }
+
+    func removeNotificationObservers() {
+        if let wordpressSupportNotificationReceivedObserver {
+            NotificationCenter.default.removeObserver(wordpressSupportNotificationReceivedObserver)
+        }
+
+        if let wordpressSupportNotificationClearedObserver {
+            NotificationCenter.default.removeObserver(wordpressSupportNotificationClearedObserver)
+        }
+
+        wordpressSupportNotificationReceivedObserver = nil
+        wordpressSupportNotificationClearedObserver = nil
+    }
+
     private func layoutNotificationIndicatorView(_ view: UIView, to superView: UIView) {
         superView.addSubview(view)
         view.translatesAutoresizingMaskIntoConstraints = false
@@ -323,3 +355,6 @@ extension NUXViewControllerBase where Self: UIViewController, Self: UIViewContro
         WordPressAuthenticator.shared.delegate?.presentSupport(from: navigationController, sourceTag: source, lastStep: state.lastStep, lastFlow: state.lastFlow)
     }
 }
+
+private var wordpressSupportNotificationReceivedKey = 0
+private var wordpressSupportNotificationClearedKey = 0