Swift中的全局修改键按键检测

Declaration

class func addGlobalMonitorForEvents(matching mask: NSEventMask,handler block: @escaping (NSEvent) -> Void) -> Any?

installs an event monitor that receives copies of events posted to
other applications. Events are delivered asynchronously to your app
and you can only observe the event; you cannot modify or otherwise
prevent the event from being delivered to its original target
application. Key-related events may only be monitored if accessibility
is enabled or if your application is trusted for accessibility access
(see AXIsProcessTrusted()). Note that your handler will not be called
for events that are sent to your own application.

import Cocoa
class ViewController: NSViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        NSEvent.addGlobalMonitorForEvents(matching: .flagsChanged) {
            switch $0.modifierFlags.intersection(.deviceIndependentFlagsMask) {
            case [.shift]:
                print("shift key is pressed")
            case [.control]:
                print("control key is pressed")
            case [.option] :
                print("option key is pressed")
            case [.command]:
                print("Command key is pressed")
            case [.control,.shift]:
                print("control-shift keys are pressed")
            case [.option,.shift]:
                print("option-shift keys are pressed")
            case [.command,.shift]:
                print("command-shift keys are pressed")
            case [.control,.option]:
                print("control-option keys are pressed")
            case [.control,.command]:
                print("control-command keys are pressed")
            case [.option,.command]:
                print("option-command keys are pressed")
            case [.shift,.control,.option]:
                print("shift-control-option keys are pressed")
            case [.shift,.command]:
                print("shift-control-command keys are pressed")
            case [.control,.option,.command]:
                print("control-option-command keys are pressed")
            case [.shift,.command,.option]:
                print("shift-command-option keys are pressed")
            case [.shift,.command]:
                print("shift-control-option-command keys are pressed")
            default:
                print("no modifier keys are pressed")
            }
        }
    }
}