cocoaappkitnsresponder

Catch unhandled keyboard events in Cocoa

I'm working on a Cocoa app.

I would like to catch all keyboard events that are not being handled by any responder, and report them to Google Analytics.

For this purpose, I would like to set a custom NSResponder that implements keyDown: as the next responder of the current last responder.

When and where should I call setNextResponder: in order to keep my custom class the last responder?

Solution

  • From Apple docs:

    If no object is found to handle the event, the last responder in the chain invokes noResponderFor:, which for a key-down event simply beeps. Event-handling objects (subclasses of NSWindow and NSView) can override this method to perform additional steps as needed.