How to handle arrow key event in Cocoa app?

Question

How to handle arrow key event in Cocoa app?

Answer 1

In my case I wanted a presented NSViewController subclass to be able to listen to arrow key events for navigation with minimal effort. Here's the best solution I've found, a slight variation of Josh Caswell's answer.

Define an event monitor (optional), can be locally in your NSViewController subclass .m

id keyMonitor;

Then start monitoring events, for example in viewDidLoad.

keyMonitor = [NSEvent addLocalMonitorForEventsMatchingMask:NSKeyDownMask handler:^(NSEvent *event) {

    unichar character = [[event characters] characterAtIndex:0];
    switch (character) {
        case NSUpArrowFunctionKey:
            NSLog(@"Up");
            break;
        case NSDownArrowFunctionKey:
            NSLog(@"Down");
            break;
        case NSLeftArrowFunctionKey:
            NSLog(@"Left");
            break;
        case NSRightArrowFunctionKey:
            NSLog(@"Right");
            break;
        default:
            break;
    }
    return event;
}];

To remove the monitor when not required (assuming you defined it)

[NSEvent removeMonitor:keyMonitor];