import Cocoa class MyView: NSView { override init(frame frameRect: NSRect) { super.init(frame: frameRect) } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } override func becomeFirstResponder() -> Bool { return true } override var acceptsFirstResponder: Bool { return true } override func keyUp(with event: NSEvent) { print("keyUp: keyCode=\(event.keyCode)") } // the 'CMD + q' combination will quit the app // the 'CMD + t' combination will open a font setting window // the 'CMD + Space' combination will toggle the spotlight search // the 'CTRL + Space' combination will toggle the input method switching // why this can't capture the key board event like 'CMD + Space' or 'CMD + t' or 'CMD + q'? // or how capture those combinations regardless of the system-wide shortcuts? override func keyDown(with event: NSEvent) { print("keyDown: keyCode=\(event.keyCode)") if event.modifierFlags.contains(.command) { if event.keyCode == 49 { print("keyDown: CMD + Space") // if the 'CMD' and 'Space' keys were pressed both, this line is not print } else { print("keyDown: CMD + others") // here, like 'CMD' and 'j' keys were pressed both, this line is print } } else if event.modifierFlags.contains(.control) { if event.keyCode == 49 { print("keyDown: CTRL + Space") // if the 'CTRL' and 'Space' keys were pressed both, this line is not print } else { print("keyDown: CTRL + others") // here, like 'CTRL' and 'j' keys were pressed both, this line is print } } else { print("keyDown: CMD or CTRL is not pressed") } } override func flagsChanged(with event: NSEvent) { print(#function, event.keyCode) } } class ViewController: NSViewController { override func viewDidLoad() { super.viewDidLoad() } override func viewWillAppear() { super.viewWillAppear() let myview = MyView(frame: view.bounds) view.addSubview(myview) } }