Showing how to listen to all keypresses in OS X through the Cocoa API using Python and PyObjC

cocoa_keypress_monitor.py

# cocoa_keypress_monitor.py by Bjarte Johansen is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

from AppKit import NSApplication, NSApp
from Foundation import NSObject, NSLog
from Cocoa import NSEvent, NSKeyDownMask
from PyObjCTools import AppHelper

class AppDelegate(NSObject):
    def applicationDidFinishLaunching_(self, notification):
        mask = NSKeyDownMask
        NSEvent.addGlobalMonitorForEventsMatchingMask_handler_(mask, handler)

def handler(event):
    try:
        NSLog(u"%@", event)
    except KeyboardInterrupt:
        AppHelper.stopEventLoop()

def main():
    app = NSApplication.sharedApplication()
    delegate = AppDelegate.alloc().init()
    NSApp().setDelegate_(delegate)
    AppHelper.runEventLoop()
    
if __name__ == '__main__':
    main()