How to check if Option key is down when user clicks a NSButton

Question

I have a few checkboxes along with textfields on a NSPanel that opens to get user parameters. As an option, I'd like the user to be able to set/unset all the checkboxes on the panel by holding the option key when they press any of the checkboxes.

I'm not sure where/how to check what the key board is doing when the user clicks the button.

score 19 · Accepted Answer · answered May 13 '13 at 23:48

19

check [NSEvent modifierFlags]...

if ([NSEvent modifierFlags ] & NSAlternateKeyMask)
{
    //do something
}

answered May 13 '13 at 23:48

Grady Player

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1

This was indeed true and a great approach up to Monterey, but I'm seeing modifierFlags always be 0 on Ventura; details [on a sample project I provided today to Apple for FB11723708](https://github.com/cdf1982/ModifierFlagsChecker). – cdf1982 Oct 27 '22 at 15:23
1

pretty interesting @cdf1982 ... just wondering if you check the even being passed into the action rather than NSEvent.currentEvent if it is different... I don't have Ventura on anything yet so I can't really poke around... – Grady Player Oct 27 '22 at 15:45
1

I didn't think of checking the event passed into `mouseDown:`, thank you @GradyPlayer! Sadly, it's the same event as `NSApp.currentEvent`, but it was worth a try. I'm exploring, with a bit of repulsion, the idea of importing Carbon and then use `GetCurrentKeyModifiers()`, as that method is returning "512" each time Shift is down, which is what I'm trying to check. Adding a Carbon import at the end of 2022 sounds less than ideal, but for a temporary fix... – cdf1982 Oct 28 '22 at 04:31
On macOS Monterey 12.6.1 (21G215) I have found a workaround: just add !0 and it works again. BOOL altKeyPressed = ([event modifierFlags ] & NSEventModifierFlagOption) != 0; – Leonardo Nov 02 '22 at 23:09

score 5 · Answer 2 · edited Mar 23 '18 at 01:35

5

Just my 2c, a Swift 3 version:

if NSEvent.modifierFlags().contains(NSEventModifierFlags.command) {
    print("Bingo")
}

One can see the rest of the flags in the documentation for NSEventModifierFlags.

edited Mar 23 '18 at 01:35

Paulo Mattos

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answered Oct 28 '16 at 11:24

user2626974

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score 1 · Answer 3 · answered Apr 30 '19 at 16:33

1

Update: NSAlternateKeyMask is now deprecated. Use NSEventModifierFlagOption instead.

See NSEventModifierFlags for a complete overview about all modifier flags.

answered Apr 30 '19 at 16:33

fbitterlich

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score 1 · Answer 4 · answered Apr 18 '21 at 04:32

Swift 5 - Also helps distinguish between the "up" and "down" presses of Option key

override func flagsChanged(with event: NSEvent) {
    print(event)
    
    if event.keyCode == 58 && event.modifierFlags.contains(NSEvent.ModifierFlags.option){
        print("Option Key is down!")
    }
    else if(event.keyCode == 58)
    {
        print("Option Key is up!")
    }
}

JZAU · Answer 5 · 2017-07-15T03:17:24.753

0

It's for someone who using swift and struggling with this.

if NSEvent.modifierFlags.rawValue & NSEvent.ModifierFlags.command.rawValue != 0 {
    // to do something.
}

edited Jul 15 '17 at 03:17

answered May 09 '16 at 06:00

JZAU

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score 0 · Answer 6 · answered Jul 05 '16 at 17:53

0

Swift 2.2:

if NSEvent.modifierFlags().contains(.AlternateKeyMask) {
    print("Option key pressed")
}

answered Jul 05 '16 at 17:53

Klaas

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score 0 · Answer 7 · answered Sep 27 '19 at 00:49

On macOS 10.14, when called from a NSGestureRecognizerDelegate method in ObjC, [NSEvent modifierFlags] was always returning 0 for me, regardless of what keys were down. I was able to reliably work around this by using [NSApp currentEvent] instead of NSEvent.

- (BOOL)isOptionKeyDown {
    NSEventModifierFlags keyEventFlags = [[NSApp currentEvent] modifierFlags] & NSEventModifierFlagDeviceIndependentFlagsMask;
    return (keyEventFlags & NSEventModifierFlagOption) != 0;
}

iphaaw · Answer 8 · 2019-08-19T08:13:12.647

-1

Swift 4:

func optionKeyPressed() -> Bool
{        
    let optionKey = NSEvent.modifierFlags.contains(NSEvent.ModifierFlags.option)
    return optionKeyPressed
}

if optionKeyPressed()
{
    print ("option key pressed")
}

edited Aug 19 '19 at 08:13

answered Aug 19 '19 at 07:34

iphaaw

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How to check if Option key is down when user clicks a NSButton

8 Answers8