Question

I am using flagsChanged in NSView to trigger events when a modifier key is pressed or released. However, I do not quite understand how to get the actual new state of the key when this happens, short of checking the state of each modifier key manually. I am currently using my own state array to check it, but this seems wrong and is not reliable. How do I do this correctly?

Answer 1

Just check the event that gets passed into flagsChanged: against the various modifier key masks that you’re interested in:

- (void)flagsChanged:(NSEvent *)theEvent {
   if (([theEvent modifierFlags] & NSAlternateKeyMask) == NSAlternateKeyMask) {
       // Do something based on the alt/option key being pressed
    } else if (([theEvent modifierFlags] & NSCommandKeyMask) == NSCommandKeyMask){
       // Do something based on the command key being pressed
    }
}