How can I handle ESC key in Cocoa app? - cocoa

Question

I made an app switching to full screen mode. I want to use ESC key to escaping fullscreen mode, but binding menu item to ESC key in IB is removed at runtime. How can I keep ESC key binding to a menu item?

Answer 1

Preferred way to handle escape key in Cocoa is this as like #Josh Caswell said.
#pragma mark - NSResponder
- (void)cancelOperation:(id)sender
{
[self exitFullScreen];
}

Answer 2

One way to capture keyboard events involves subclassing:
Subclass your full-screen class (e.g.) NSView.
Add the method - (void) keyDown:(NSEvent *)theEvent to the subclass implementation.
Open up InterfaceBuilder and select the full-screen class that you previously created.
Change its class to your new subclass.
The subclass looks something like:
MySubclass.h
#interface MySubclass : NSView {
}
#end
MySubclass.m
#import <Carbon/Carbon.h>
#implementation MySubclass
- (void)keyDown:(NSEvent *)theEvent
{
switch([theEvent keyCode]) {
case kVK_Escape:
NSLog(#"ESC");
// Call the full-screen mode method
break;
default:
[super keyDown:theEvent];
}
}
#end
This doesn't bind the ESC key to the menu item, but it does give you equivalent functionality (and a bit more flexability since you can intercept all keyboard events).

Answer 3

Many people try to implement esc key functionality. There is cancelOperation in the responder chain to handle escape events.
//WRONG
- (void)keyDown:(NSEvent *)event
{
//unichar character = 0;
//if ([event type] == NSEventTypeKeyDown) {
// if ([[event charactersIgnoringModifiers] length] == 1) {
// character = [[event characters] characterAtIndex:0];
// }
//}
switch (character) {
//THIS IS WRONG correct is to implement interpretKeyEvents+moveRight
//case NSRightArrowFunctionKey:
// [self moveSelectedIndexRight];
// break;
//THIS IS WRONG correct is to implement interpretKeyEvents+ moveLeft
//case NSLeftArrowFunctionKey:
// [self moveSelectedIndexLeft];
// break;
//THIS IS WRONG correct is to implement interpretKeyEvents+ moveLeft
//case NSCarriageReturnCharacter:
// [self dismissWithCurrentlySelectedToken];
// break;
default:
[self interpretKeyEvents:#[event]];
[super keyDown:event]
break;
}
}
//CORRECT
- (void)keyDown:(NSEvent *)event
{
[self interpretKeyEvents:#[event]];
[super keyDown:event];
}
`/* Catch the commands interpreted by interpretKeyEvents:. Normally, if we don't implement (or any other view in the hierarchy implements) the selector, the system beeps. Menu navigation generally doesn't beep, so stop doCommandBySelector: from calling up t`he hierarchy just to stop the beep.
*/
- (void)doCommandBySelector:(SEL)selector {
if ( selector == #selector(moveRight:)
|| selector == #selector(moveLeft:)
|| selector == #selector(cancelOperation:)
|| selector == #selector(insertNewline:) )
{
[super doCommandBySelector:selector];
}
// do nothing, let the menu handle it (see call to super in -keyDown:)
// But don't call super to prevent the system beep
}
- (void)cancelOperation:(id)sender
{
//do your escape stuff
}
- (void)insertNewline:(id)sender
{
//do your enter stuff
}
- (void)moveRight:(nullable id)sender
{
[self moveSelectedIndexRight];
}
- (void)moveLeft:(nullable id)sender
{
[self moveSelectedIndexLeft];
}

Answer 4

I needed to dodge WKWebView crashes when ESC is pressed(?) so I sub-class it, and added:
import Carbon.HIToolbox
override func keyDown(with event: NSEvent) {
if event.keyCode == UInt16(kVK_Escape) {
// We crash otherwise, so just close window
self.window?.performClose(event)
}
else
{
// still here?
super.keyDown(with: event)
}
}