Vfrdtyky

Is there an official API for reading the current settings in "System Preferences > Keyboard > Modifier Keys ..." on OSX (10.11.6 hopefully in a forward-compatible manner) from a C program (Carbon/CoreFoundation ...) which intended to run from command line (no UI)?

I have seen How can I change modifier keys in "System Preferences > Keyboard > Modifier Keys..." and (referenced) Does anyone know where OSX stores the settings in System Preferences > Keyboard > Modifier Keys? but neither provide an "official" API.

I also came across Replacement for deprecated NXOpenEventStatus? answer while digging in IOHID headers and using keywords to search. It seemed promising looking at the output which contained HIDKeyboardModifierMappingPairs. However, running the answer's example shows an empty HIDKeyboardModifierMappingPairs CFArray.

Pasting the code for ease of reference and output snippet:

#import <Foundation/Foundation.h>

#import <IOKit/hidsystem/IOHIDLib.h>

#import <IOKit/hidsystem/IOHIDParameter.h>



int main(int argc, const char * argv) {

    @autoreleasepool {

        io_service_t service = IORegistryEntryFromPath(kIOMasterPortDefault, kIOServicePlane ":/IOResources/IOHIDSystem");



        CFDictionaryRef parameters = IORegistryEntryCreateCFProperty(service, CFSTR(kIOHIDParametersKey), kCFAllocatorDefault, kNilOptions);

        NSLog(@"%@", parameters);



        IOObjectRelease(service);

    }

    return 0;

}

and output snippet:

2018-11-10 17:32:38.564 iohidparam_mout[22543:1699981] {

    ...

    HIDKeyboardModifierMappingPairs =     (

    );

    ...

}

Bonus: Is there a notification service for when the user updates these settings through System Preferences?