Objective-C/Cocoa: Detect all keypresses

Question

Is it possible to run a method every time the user presses a key. Basically I want to run a sound like on the iPhone or iPad when a key is pressed. I do not want to detect key presses in my window or in a certain control, I want to detect ALL presses (such as when they are typing in Safari or something. I do not need to know what the key is.

Thanks

Answer 1

Use CGEventTapCreate documented here:

https://developer.apple.com/library/mac/#documentation/Carbon/Reference/QuartzEventServicesRef/Reference/reference.html

Or use NSEvents addGlobalMonitorForEventsMatchingMask:handler: documented here:

https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/nsevent_Class/Reference/Reference.html

NSEvent Example:

[NSEvent addGlobalMonitorForEventsMatchingMask:(NSKeyDownMask) handler:^(NSEvent *event){
    [self keyWasPressedFunction: event];
    //Or just put your code here
}];

I would say NSEvents are easier...

Note:

For security reasons, Apple requires you have "Enable access for assistive devices" turned on in System Preferences, in order to use ether of the above methods.