listen keyboard event globally in appkit

To listen to keyboard events globally in AppKit, you can use the NSEvent class and its addGlobalMonitorForEventsMatchingMask method. Here's an example:

import AppKit

class AppDelegate: NSObject, NSApplicationDelegate {

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        // Add global monitor for key down events
        NSEvent.addGlobalMonitorForEvents(matching: .keyDown) { event in
            // Handle key down event
            if let keyEvent = event as? NSEvent {
                let keyCode = keyEvent.keyCode
                print("Key down event: \(keyCode)")
            }
        }
        
        // Add global monitor for key up events
        NSEvent.addGlobalMonitorForEvents(matching: .keyUp) { event in
            // Handle key up event
            if let keyEvent = event as? NSEvent {
                let keyCode = keyEvent.keyCode
                print("Key up event: \(keyCode)")
            }
        }
    }
    
    // ...
}

// Instantiate AppDelegate and run the app
let delegate = AppDelegate()
NSApplication.shared.delegate = delegate
NSApplication.shared.run()

In this example, we add global monitors for key down and key up events using NSEvent.addGlobalMonitorForEventsMatchingMask. The closure passed to the method is called whenever a matching event occurs globally.

Inside the closure, you can handle the key events as needed. In this example, we simply print the key code to the console.

Make sure to set the AppDelegate as the delegate of the NSApplication before running the app