Use Qt signal for macOS Dock icon click event

This moves the Dock icon click reaction code to the common place and
allows some cleanup in obj_c code.

According to the Apple's docs `class_replaceMethod` behaves as
`class_addMethod`, if the method identified by name does not yet exist;
or as `method_setImplementation`, if it does exist.

1 files changed, 12 insertions, 6 deletions

diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 5d34b8c7b0..8817f93b79 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -595,7 +595,7 @@ void BitcoinGUI::createTrayIcon(const NetworkStyle *networkStyle)
 void BitcoinGUI::createTrayIconMenu()
 {
 #ifndef Q_OS_MAC
-    // return if trayIcon is unset (only on non-Mac OSes)
+    // return if trayIcon is unset (only on non-macOSes)
     if (!trayIcon)
         return;
 
@@ -604,15 +604,15 @@ void BitcoinGUI::createTrayIconMenu()
 
     connect(trayIcon, &QSystemTrayIcon::activated, this, &BitcoinGUI::trayIconActivated);
 #else
-    // Note: On Mac, the dock icon is used to provide the tray's functionality.
+    // Note: On macOS, the Dock icon is used to provide the tray's functionality.
     MacDockIconHandler *dockIconHandler = MacDockIconHandler::instance();
-    dockIconHandler->setMainWindow(static_cast<QMainWindow*>(this));
+    connect(dockIconHandler, &MacDockIconHandler::dockIconClicked, this, &BitcoinGUI::macosDockIconActivated);
     trayIconMenu = dockIconHandler->dockMenu();
 #endif
 
-    // Configuration of the tray icon (or dock icon) icon menu
+    // Configuration of the tray icon (or Dock icon) menu
 #ifndef Q_OS_MAC
-    // Note: On Mac, the dock icon's menu already has show / hide action.
+    // Note: On macOS, the Dock icon's menu already has Show / Hide action.
     trayIconMenu->addAction(toggleHideAction);
     trayIconMenu->addSeparator();
 #endif
@@ -626,7 +626,7 @@ void BitcoinGUI::createTrayIconMenu()
         trayIconMenu->addAction(openRPCConsoleAction);
     }
     trayIconMenu->addAction(optionsAction);
-#ifndef Q_OS_MAC // This is built-in on Mac
+#ifndef Q_OS_MAC // This is built-in on macOS
     trayIconMenu->addSeparator();
     trayIconMenu->addAction(quitAction);
 #endif
@@ -641,6 +641,12 @@ void BitcoinGUI::trayIconActivated(QSystemTrayIcon::ActivationReason reason)
         toggleHidden();
     }
 }
+#else
+void BitcoinGUI::macosDockIconActivated()
+{
+    show();
+    activateWindow();
+}
 #endif
 
 void BitcoinGUI::optionsClicked()