问OSX键盘快捷键后台应用程序，如何

EN

OSStatus HotKeyEventHandlerProc(EventHandlerCallRef inCallRef, EventRef ev, void* inUserData) {
    OSStatus err = noErr;
    if(GetEventKind(ev) == kEventHotKeyPressed) {
        [(id)inUserData handleKeyPress];
    } else if(GetEventKind(ev) == kEventHotKeyReleased) {
        [(id)inUserData handleKeyRelease];
    } else err = eventNotHandledErr;
    return err;
}

//EventHotKeyRef hotKey; instance variable

- (void)installEventHandler {
    static BOOL installed = NO;
    if(installed) return;
    installed = YES;
    const EventTypeSpec hotKeyEvents[] = {{kEventClassKeyboard,kEventHotKeyPressed},{kEventClassKeyboard,kEventHotKeyReleased}};
    InstallApplicationEventHandler(NewEventHandlerUPP(HotKeyEventHandlerProc),GetEventTypeCount(hotKeyEvents),hotKeyEvents,(void*)self,NULL);
}

- (void)registerHotKey {
    [self installEventHandler];
    UInt32 virtualKeyCode = ?; //The virtual key code for the key
    UInt32 modifiers = cmdKey|shiftKey|optionKey|controlKey; //remove the modifiers you don't want
    EventHotKeyID eventID = {'abcd','1234'}; //These can be any 4 character codes. It can be used to identify which key was pressed
    RegisterEventHotKey(virtualKeyCode,modifiers,eventID,GetApplicationEventTarget(),0,(EventHotKeyRef*)&hotKey);
}
- (void)unregisterHotKey {
    if(hotkey) UnregisterEventHotKey(hotKey);
    hotKey = 0;
}

- (void)handleHotKeyPress {
    //handle key press
}
- (void)handleHotKeyRelease {
    //handle key release
}