Use NotificationCenter to trigger find action

Author: dteoh

devdocs-macos/AppDelegate.swift

@@ -1,5 +1,10 @@
 import AppKit
 
+public extension Notification.Name {
+    static let MenuFindAction = Notification.Name(
+        rawValue: "AppDelegateMenuFindActionNotification")
+}
+
 @NSApplicationMain
 class AppDelegate: NSObject, NSApplicationDelegate {
     func applicationWillFinishLaunching(_ notification: Notification) {
@@ -25,10 +30,6 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     }
 
     @IBAction func performFindAction(_ sender: Any) {
-        guard let window = NSApp.mainWindow else { return }
-        let dwc = window.windowController.map { wc in
-            wc as! DocumentationWindowController
-        }
-        dwc?.activateFind()
+        NotificationCenter.default.post(name: .MenuFindAction, object: nil)
     }
 }

devdocs-macos/DocumentationWindowController.swift

@@ -40,13 +40,15 @@ class DocumentationWindowController: NSWindowController {
                                                selector: #selector(observeDocumentURL),
                                                name: .DocumentURLDidChange,
                                                object: dvc)
-    }
 
-    func activateFind() {
-        guard let dvc = documentationViewController else { return }
-        dvc.showSearchControl()
+        NotificationCenter.default.addObserver(self,
+                                               selector: #selector(observeMenuFindAction),
+                                               name: .MenuFindAction,
+                                               object: nil)
     }
 
+    // MARK:- NotificationCenter observers
+
     @objc private func observeViewerState() {
         guard let dvc = documentationViewController else { return }
 
@@ -77,6 +79,18 @@ class DocumentationWindowController: NSWindowController {
         self.documentation.url = dvc.documentURL
     }
 
+    @objc private func observeMenuFindAction() {
+        guard let window = self.window else { return }
+        if !window.isKeyWindow {
+            return
+        }
+
+        guard let dvc = documentationViewController else { return }
+        dvc.showSearchControl()
+    }
+
+    // MARK:- KVO observers
+
     private func observeEffectiveAppearance() {
         guard let window = self.window else { return }
         observations.insert(