Question

I’m working with an application that allows the customer to customize what shortcut keys are assigned. One thing I want to do is warn if a shortcut key is chosen that is already in use by Mac OS X.

I’m trying to work with CopySymbolicHotKeys, but I’m not sure that I’m using it correctly as it lists commands as being reserved even though I do not see it listed in the “Keyboard Shortcuts” tab-pane of the “Keyboard & Mouse” System Preferences. I would like to be able to get those shortcuts that are “reserved” for system use, is this the API to use?

I’ve included a sample of my code below, please look at it an offer any suggestion that may come to your mind.

CFArrayRef hotkeyArray = NULL;
OSStatus status = CopySymbolicHotKeys(&hotkeyArray);

if (noErr == status && NULL != hotkeyArray) {

    CFIndex hotKeyCount = CFArrayGetCount(hotkeyArray);

    for (CFIndex i = 0; i < hotKeyCount; i++) {
        CFDictionaryRef hotKeyDict = (CFDictionaryRef) CFArrayGetValueAtIndex(hotkeyArray, i);
        if (hotKeyDict && CFGetTypeID(hotKeyDict) == CFDictionaryGetTypeID()) {
            if (kCFBooleanTrue == (CFBooleanRef) CFDictionaryGetValue(hotKeyDict, kHISymbolicHotKeyEnabled)) {

                SInt32 keyModifiers = 0;

                CFNumberRef cfkeyModifers = (CFNumberRef) CFDictionaryGetValue(hotKeyDict, kHISymbolicHotKeyModifiers);
                CFNumberGetValue(cfkeyModifers, kCFNumberSInt32Type, &keyModifiers);

                bool keyIsCommandOnly = (keyModifiers == (keyModifiers & cmdKey));
                bool keyIsCommandAndOption = (keyModifiers == (keyModifiers & (cmdKey | optionKey)));

                CFNumberRef cfKeyCode = (CFNumberRef) CFDictionaryGetValue(hotKeyDict, kHISymbolicHotKeyCode);

                short keyCode = 0;
                CFNumberGetValue(cfKeyCode, kCFNumberShortType, &keyCode);

                CFStringRef keyString = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("%C"), keyCode);

                const char* commandOnlyStr = "Command";
                const char* commandAndOptionStr = "Command-Option";
                const char* otherStr = "Other Modifier Key";

                char* modifierStr = otherStr;

                if (keyIsCommandOnly) {
                    modifierStr = commandOnlyStr;
                }
                else if (keyIsCommandAndOption) {
                    modifierStr = commandAndOptionStr;
                }

                CFStringRef debugString = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("Mac OS X Reserved Key: %s %@"), modifierStr, keyString);
                CFShow(debugString); // Command-O, Command-W and other apparently non-reserved keys are output
                CFRelease(debugString);
                CFRelease(keyString);
            }
        }
    }
}
CFRelease(hotkeyArray);

Answer 1

I don’t think that this is possible.

This link discusses using CopySymbolicHotKeys as well. However, the function lists keyboard shortcuts that are not listed in the System Preference for Keyboard Shortcuts. If there was someway to differentiate between actually reserved keys and just standard keys, that would be ideal.

The best answer seems to be parsing the actual plist file, “com.apple.symbolichotkeys.plist” which I found in Apple’s Carbon Email Discussion List. However, this answer assumes that you know what each and every key is (which I don’t).

I also found a link describing what the modifier key values are.

Here is the code that was posted for disabling a known key in the System Shortcut Key Preferenes:

#include <CoreServices/CoreServices.h>

static CFStringRef gApplicationID = CFSTR("com.apple.symbolichotkeys");

static CFStringRef gKeyASHK =       CFSTR("AppleSymbolicHotKeys");
static CFStringRef gKey73 =         CFSTR("73");
static CFStringRef gKeyEnabled =    CFSTR("enabled");

int main(int argc, const char *argv[]) {
    #pragma unused (argc, argv)

    CFPropertyListRef hotkeysCFPropertyListRef = CFPreferencesCopyAppValue(gKeyASHK, gApplicationID);
    if ( !hotkeysCFPropertyListRef ) {
        fprintf(stderr,
                "%s, CFPreferencesCopyAppValue(\"AppleSymbolicHotKeys\", \"com.apple.symbolichotkeys.plist\" returned NULL.\n",
                __PRETTY_FUNCTION__);
        return (-1);
    }
    // make sure it's a dictionary
    if ( CFGetTypeID(hotkeysCFPropertyListRef) != CFDictionaryGetTypeID() ) {
        fprintf(stderr, "%s, CFGetTypeID(hotkeysCFPropertyListRef) != CFDictionaryGetTypeID().\n", __PRETTY_FUNCTION__);
        return (-1);
    }

    // get the "73" value from that dictionary
    CFPropertyListRef hotkey73CFPropertyListRef = NULL;
    if ( !CFDictionaryGetValueIfPresent(hotkeysCFPropertyListRef, gKey73, &hotkey73CFPropertyListRef) ) {
        fprintf(stderr, "%s, CFDictionaryGetValueIfPresent(...,\"73\",...) returned FALSE.\n", __PRETTY_FUNCTION__);
        return (-1);
    }
    //CFShow(hotkey73CFPropertyListRef);
    // make sure it's a dictionary
    if ( CFGetTypeID(hotkey73CFPropertyListRef) != CFDictionaryGetTypeID() ) {
        fprintf(stderr, "%s, CFGetTypeID(hotkey73CFPropertyListRef) != CFDictionaryGetTypeID().\n", __PRETTY_FUNCTION__);
        return (-1);
    }

    // get the "73" value from that dictionary
    CFPropertyListRef hotkey73EnabledCFPropertyListRef = NULL;
    if ( !CFDictionaryGetValueIfPresent(hotkey73CFPropertyListRef, gKeyEnabled, &hotkey73EnabledCFPropertyListRef) ) {
        fprintf(stderr, "%s, CFDictionaryGetValueIfPresent(...,\"enabled\",...) returned FALSE.\n", __PRETTY_FUNCTION__);
        return (-1);
    }
    //CFShow(hotkey73EnabledCFPropertyListRef);
    // make sure it's a boolean
    if ( CFGetTypeID(hotkey73EnabledCFPropertyListRef) != CFBooleanGetTypeID() ) {
        fprintf(stderr, "%s, CFGetTypeID(hotkey73EnabledCFPropertyListRef) != CFBooleanGetTypeID().\n", __PRETTY_FUNCTION__);
        return (-1);
    }

    // get its value
    Boolean value = CFBooleanGetValue(hotkey73EnabledCFPropertyListRef);

    CFBooleanRef hotkey73EnabledCFBooleanRef = value ? kCFBooleanFalse : kCFBooleanTrue;    // note: toggle value

    // create a mutable copy of the hot key 73 dictionary
    CFMutableDictionaryRef newHotkey73CFCFMutableDictionaryRef = CFDictionaryCreateMutableCopy(kCFAllocatorDefault, 0,  hotkey73CFPropertyListRef);
    if ( !newHotkey73CFCFMutableDictionaryRef ) {
        fprintf(stderr, "%s, CFDictionaryCreateMutableCopy(..., hotkey73CFPropertyListRef) returned NULL.\n", __PRETTY_FUNCTION__);
        return (-1);
    }

    // set the new value for the "enabled" item
    CFDictionarySetValue(newHotkey73CFCFMutableDictionaryRef, gKeyEnabled, hotkey73EnabledCFBooleanRef);
    //CFShow(newHotkey73CFCFMutableDictionaryRef);

    // create a mutable copy of the hot key dictionary
    CFMutableDictionaryRef newHotkeysCFPropertyListRef = CFDictionaryCreateMutableCopy(kCFAllocatorDefault, 0, hotkeysCFPropertyListRef);
    if ( !newHotkeysCFPropertyListRef ) {
        fprintf(stderr, "%s, CFDictionaryCreateMutableCopy(...,hotkeysCFPropertyListRef) returned NULL.\n", __PRETTY_FUNCTION__);
        return (-1);
    }

    // set the new value for the "73" item
    CFDictionarySetValue(newHotkeysCFPropertyListRef, gKey73, newHotkey73CFCFMutableDictionaryRef);
    CFRelease(newHotkey73CFCFMutableDictionaryRef);
    //CFShow(newHotkeysCFPropertyListRef);

    CFPreferencesSetAppValue(gKeyASHK, newHotkeysCFPropertyListRef, gApplicationID);
    if ( !CFPreferencesAppSynchronize(gApplicationID) ) {
        fprintf(stderr, "%s, CFPreferencesAppSynchronize returned false.\n", __PRETTY_FUNCTION__);
        return (-1);
    }

    // note: value is opposite of what we just set (so invert logic)
    printf("%s, /AppleSymbolicHotKeys/73/enabled set to %s.\n", __PRETTY_FUNCTION__, value ? "FALSE" : "TRUE");

    return (0);
} // main