Handling cocoa key events (keys pressed) with swift in a console application

Question

Ok so i'm trying to log on console output what keys are pressed. I just can't understand the cocoa structure, neither with Obj-c, nor swift. I'm not a master in these 2 languages but... Well here's my code:

import Cocoa
import Foundation
import AppKit

var loop = true
var idRegisterdEvent: AnyObject? = nil

func handlerEvent(myEvent: (NSEvent!)) -> Void {
    print(myEvent.keyCode)
}

while loop {

    idRegisterdEvent = NSEvent.addGlobalMonitorForEventsMatchingMask(NSEventMask.KeyDownMask, handler: handlerEvent)
}

i know everything is wrong, yeah.. But man, these events, i can't understand how they work.

Answer 1

After spending a couple of hours on google I eventually read a couple of github resources. It turns out that someone has already figured it out.

Basically you need to create a NSApplicationDelegate, which enables your app to listen to system-events.

The following shows the bare minimum code needed(swift2):

func acquirePrivileges() -> Bool {
    let accessEnabled = AXIsProcessTrustedWithOptions(
        [kAXTrustedCheckOptionPrompt.takeUnretainedValue() as String: true])

    if accessEnabled != true {
        print("You need to enable the keylogger in the System Preferences")
    }
    return accessEnabled == true
}

class ApplicationDelegate: NSObject, NSApplicationDelegate {
    func applicationDidFinishLaunching(notification: NSNotification?) {

        acquirePrivileges()
        // keyboard listeners
        NSEvent.addGlobalMonitorForEventsMatchingMask(
            NSEventMask.KeyDownMask, handler: {(event: NSEvent) in
                print(event)
        })
    }
}

// preparing main loop
let application = NSApplication.sharedApplication()
let applicationDelegate = MyObserver()
application.delegate = applicationDelegate
application.activateIgnoringOtherApps(true)
application.run()

If you are just interested in only catching non-accessibility events (e.g.: NSWorkspaceDidActivateApplicationNotification) you can get away with much fewer lines of code as you only need NSRunLoop.mainRunLoop().run(). I only added this example since I saw your while true event-loop, which never will let you listen to any system-events, since its blocking the main-thread.

class MyObserver: NSObject
{
    override init() {
        super.init()

        // app listeners
        NSWorkspace.sharedWorkspace().notificationCenter.addObserver(self, selector: "SwitchedApp:", name: NSWorkspaceDidActivateApplicationNotification, object: nil)
    }

    func SwitchedApp(notification: NSNotification!)
    {
        print(notification)    
    }
}


let observer = MyObserver()

// simply to keep the command line tool alive - as a daemon process
NSRunLoop.mainRunLoop().run()

Answer 2

As a first step towards the solution I suggest to make sure the local version of the monitor works:

NSEvent.addLocalMonitorForEventsMatchingMask(NSEventMask.KeyDownMask, handler: {(evt: NSEvent!) -> NSEvent in
    NSLog("Local Keydown: " + evt.characters! + " (" + String(evt.keyCode) + ")");
    return evt;
});

If it works, go onto the global version:

NSEvent.addGlobalMonitorForEventsMatchingMask(NSEventMask.KeyDownMask, handler: {(evt: NSEvent!) -> Void in
    NSLog("Global Keydown: " + evt.characters! + " (" + String(evt.keyCode) + ")");
});

If the local works, but the global doesn't, this means you didn't enable your app (or while developing, XCode) in [System Preferences / Security & Privacy / Accessibility] to control your computer.

If none of them works, then maybe it doesn't work with console applications at all...