전역 단축키: 조합 키, 수정 키 하나, 이름 없는 키

import AppKit
import Carbon.HIToolbox

/// kVK_F1 is 0x7A and kVK_F12 is 0x6F: the function keys are not a range.
let functionKeyCodes: Set<UInt16> = Set([
    kVK_F1, kVK_F2, kVK_F3, kVK_F4, kVK_F5, kVK_F6, kVK_F7, kVK_F8, kVK_F9, kVK_F10,
    kVK_F11, kVK_F12, kVK_F13, kVK_F14, kVK_F15, kVK_F16, kVK_F17, kVK_F18, kVK_F19, kVK_F20,
].map { UInt16($0) })

func carbonModifiers(from flags: NSEvent.ModifierFlags) -> UInt32 {
    var mask: UInt32 = 0
    if flags.contains(.command) { mask |= UInt32(cmdKey) }
    if flags.contains(.option) { mask |= UInt32(optionKey) }
    if flags.contains(.control) { mask |= UInt32(controlKey) }
    if flags.contains(.shift) { mask |= UInt32(shiftKey) }
    return mask
}

@MainActor
final class HotkeyCenter {
    private var handler: EventHandlerRef?
    private var refs: [UInt32: EventHotKeyRef] = [:]
    private var actions: [UInt32: () -> Void] = [:]
    private var nextID: UInt32 = 1

    /// Returns nil on success, or a message naming the chord that could not be registered.
    func register(keyCode: UInt16, modifiers: NSEvent.ModifierFlags, label: String,
                  action: @escaping () -> Void) -> String? {
        if handler == nil {
            var spec = EventTypeSpec(eventClass: OSType(kEventClassKeyboard), eventKind: UInt32(kEventHotKeyPressed))
            InstallEventHandler(GetApplicationEventTarget(), { _, event, userData in
                var hotKeyID = EventHotKeyID()
                GetEventParameter(event, EventParamName(kEventParamDirectObject), EventParamType(typeEventHotKeyID),
                                  nil, MemoryLayout<EventHotKeyID>.size, nil, &hotKeyID)
                let center = Unmanaged<HotkeyCenter>.fromOpaque(userData!).takeUnretainedValue()
                let id = hotKeyID.id
                Task { @MainActor in center.actions[id]?() }
                return noErr
            }, 1, &spec, Unmanaged.passUnretained(self).toOpaque(), &handler)
        }
        var ref: EventHotKeyRef?
        let id = EventHotKeyID(signature: OSType(0x5350524B), id: nextID)   // 'SPRK'
        let status = RegisterEventHotKey(UInt32(keyCode), carbonModifiers(from: modifiers), id,
                                         GetApplicationEventTarget(), 0, &ref)
        guard status == noErr, let ref else { return "\(label) is already taken (\(status))" }
        refs[nextID] = ref
        actions[nextID] = action
        nextID += 1
        return nil
    }
}

import AppKit
import Carbon.HIToolbox

@MainActor
final class HoldToTalk {
    private var monitors: [Any] = []
    private let keyCode = CGKeyCode(kVK_RightCommand)
    private var held = false

    func start(onChange: @escaping @MainActor (Bool) -> Void) {
        let handle: (NSEvent) -> Void = { [weak self] event in
            guard let self, event.keyCode == UInt16(self.keyCode) else { return }
            // The flag alone lies while the LEFT Command key is also down. Ask the key itself.
            let down = CGEventSource.keyState(.combinedSessionState, key: self.keyCode)
            if down != self.held { self.held = down; onChange(down) }
        }
        if let global = NSEvent.addGlobalMonitorForEvents(matching: .flagsChanged, handler: { event in
            MainActor.assumeIsolated { handle(event) }
        }) { monitors.append(global) }
        if let local = NSEvent.addLocalMonitorForEvents(matching: .flagsChanged, handler: { event in
            handle(event); return event
        }) { monitors.append(local) }
    }
}