Unlocking macOS: Can You Programmatically Link Keyboard Shortcuts to Action Names?

Determining the specific action name (like "Copy", "Paste", or a custom app function) triggered by a particular keyboard shortcut identifier using macOS APIs isn't a simple task with a single, universal solution. The connection between a shortcut and its action is often managed internally by individual applications or through user customizations, rather than a centralized, publicly queryable system database.

However, by combining several macOS frameworks and approaches, you can often piece together this information, depending on the context of the shortcut (system-wide, application-specific, user-defined).

Key Insights

No Single API Solution: macOS lacks a dedicated public API to directly translate any keyboard shortcut ID into its action name across all applications.
Application-Centric Mapping: Most keyboard shortcuts are defined and handled within the application they belong to, often linked directly to menu items.
Multiple APIs Required: Retrieving this information generally involves querying different sources like application menus (AppKit), user preferences (NSUserDefaults), and potentially using Accessibility APIs for broader inspection.

The Challenge: Why Isn't It Straightforward?

Several factors contribute to the complexity of mapping shortcut IDs to action names programmatically:

Decentralized Management: Each application typically manages its own shortcuts. While macOS provides frameworks for this, there's no central registry that external processes can easily query for action names based on key combinations.
Internal Application Logic: The precise code that links a shortcut press to an action (e.g., calling a specific function) resides within the application and isn't exposed through a standardized public API for external discovery.
User Customization: Users can redefine shortcuts via System Settings > Keyboard > Shortcuts. These customizations are stored in preference files (often using NSUserKeyEquivalents), but accessing and interpreting this data reliably across all apps and system versions isn't guaranteed by a stable API.
Context Sensitivity: The same shortcut might perform different actions depending on the active application, window, or even the selected element within an application.
Dynamic Shortcuts: Some shortcuts might be created or enabled/disabled dynamically by applications based on the current state.

Exploring the macOS Toolbox: Relevant APIs and Frameworks

While no single function exists, several APIs and frameworks can be leveraged, often in combination, to approach this problem:

1. AppKit Framework (NSMenu & NSMenuItem)

Inspecting Application Menus

For many applications built with AppKit, keyboard shortcuts are directly associated with menu items (NSMenuItem). You can programmatically inspect an application's menu bar (NSMenu) to find items matching a specific shortcut.

How it works: Iterate through the NSMenuItem objects within an application's NSMenu. Each item has properties like keyEquivalent (the character key) and keyEquivalentModifierMask (modifier keys like Command, Shift, Option, Control).
Finding the Action Name: If a menu item's shortcut matches the one you're investigating, its title property often represents the action name (e.g., "Copy", "Save As..."). The action property provides the selector (method name) that is called, which can also indicate the action.
Limitations: This primarily works for shortcuts linked to visible menu items within standard Cocoa applications. It requires access to the application's menu structure, which might be difficult or impossible for sandboxed or non-standard applications without using other methods like Accessibility.

2. User Defaults (NSUserDefaults / CFPreferences)

Accessing User Customizations

User-defined keyboard shortcut overrides are often stored in the macOS preferences system.

How it works: Use NSUserDefaults (in Swift/Objective-C) or the defaults command-line tool to read preference domains. The NSGlobalDomain or specific application domains (e.g., com.apple.Finder) contain dictionaries like NSUserKeyEquivalents.
Finding the Action Name: This dictionary maps menu item titles (action names) to the custom shortcut assigned by the user (represented in a specific string format, e.g., @~^k for Command-Option-Control-K). You might need to parse this dictionary to find the action name associated with a known custom shortcut string.
Limitations: This only covers shortcuts explicitly customized by the user through System Settings. The format of the shortcut string representation isn't officially documented and could potentially change. Parsing requires understanding this format.

3. Accessibility API (AXUIElement)

Programmatic UI Inspection

The Accessibility API allows your application (with appropriate user permissions) to inspect the user interface elements of other running applications.

How it works: You can traverse the UI hierarchy of an application, including its menu bar and menu items.
Finding the Action Name: By finding UI elements corresponding to menu items, you can retrieve attributes like their title (action name) and associated keyboard shortcut value. This can work even for applications where direct NSMenu inspection isn't feasible.
Limitations: Requires explicit user permission to control the computer via Accessibility settings. UI scripting can be fragile and may break if an application's UI structure changes. It can also be slower and more complex than direct API calls.

Accessibility settings in macOS, crucial for enabling programmatic UI inspection.

4. Carbon Event Manager (Event Hotkeys)

Handling Global Hotkeys (Legacy)

Older macOS applications might use the Carbon framework to register system-wide "hotkeys".

How it works: APIs like RegisterEventHotKey allow applications to listen for specific key combinations globally.
Finding the Action Name: Querying registered Carbon hotkeys might be possible, but associating them back to a specific, user-friendly "action name" is often difficult as they usually trigger internal application functions.
Limitations: Carbon is largely legacy. Modern applications tend to use AppKit or other methods. Querying hotkeys registered by other applications is not a standard or straightforward operation.

5. Shortcuts Framework (ShortcutsKit)

Interacting with Modern Automation Shortcuts

For shortcuts created and managed via the macOS Shortcuts app (introduced in Monterey).

How it works: This framework allows interaction with the Shortcuts app and its library.
Finding the Action Name: You might be able to query user-created Shortcuts and their assigned keyboard triggers. The "action name" would likely be the name the user gave to their Shortcut workflow.
Limitations: This only applies to workflows created within the Shortcuts app, not traditional application menu shortcuts or system-wide hotkeys. Public APIs for deep introspection might be limited.

6. Third-Party Libraries

Simplifying Shortcut Management (Within Your App)

Libraries like KeyboardShortcuts (by sindresorhus) or HotKey (by soffes) provide convenient wrappers around macOS APIs (like Carbon or AppKit) for developers to *implement* global or user-customizable shortcuts *within their own applications*. They manage the registration and handling process. While essential for building apps with robust shortcut support, they don't typically offer a way to query the action names associated with shortcuts in *other* arbitrary applications.

7. AppleScript & System Events

Scripting UI Interactions

AppleScript can interact with System Events and application UI elements, offering another way to potentially script the process of finding menu items associated with shortcuts.

Limitations: Similar to the Accessibility API, this relies on UI structure and can be brittle. It's often slower and less robust than direct API calls.

Visualizing the Landscape: APIs and Contexts

The following diagram illustrates the different contexts where shortcuts exist and the primary APIs or methods used to interact with them:

mindmap root["Determining Action Name from Shortcut ID"] id1["Contexts"] id1_1["Application-Specific
(Menu Items)"] id1_2["User-Defined
(System Settings Override)"] id1_3["System-Wide
(Global Hotkeys)"] id1_4["Automation
(Shortcuts App)"] id2["APIs & Methods"] id2_1["AppKit (NSMenu/NSMenuItem)
- Direct inspection of app menus"] id2_2["NSUserDefaults/CFPreferences
- Read NSUserKeyEquivalents"] id2_3["Accessibility API (AX)
- Programmatic UI inspection"] id2_4["Carbon Events API
- Legacy global hotkeys"] id2_5["Shortcuts Framework
- Modern automation"] id2_6["AppleScript/System Events
- UI Scripting"] id3["Challenges"] id3_1["No Single Universal API"] id3_2["Application Internal Logic"] id3_3["Context Sensitivity"] id3_4["Permissions Required (Accessibility)"] id3_5["API Stability/Legacy Issues"]

Comparing API Suitability

Choosing the right approach depends on the specific context and requirements. This chart provides a relative comparison of the main methods based on several factors:

This chart highlights the trade-offs: AppKit is good for inspecting an app's own menus reliably, NSUserDefaults helps with user overrides, while the Accessibility API offers broader scope but requires permissions and is less reliable. Carbon is largely outdated, and the Shortcuts Framework targets a specific type of automation.

Summary of Key APIs/Frameworks

The following table summarizes the primary macOS components involved in handling keyboard shortcuts and potentially determining their associated action names:

API/Framework	Primary Use Case	Context	Key Considerations
AppKit (NSMenu/NSMenuItem)	Inspect application menu items and their shortcuts.	Application-Specific (Cocoa Apps)	Reliable for standard menu shortcuts; action name often derived from `title`. Requires access to the app's menu structure.
NSUserDefaults / CFPreferences	Read user-customized shortcut mappings (`NSUserKeyEquivalents`).	User-Defined Overrides	Accesses global or app-specific overrides set by the user. Requires parsing potentially undocumented string formats.
Accessibility API (AXUIElement)	Programmatically inspect UI elements of other applications.	System-Wide / Any Application	Broad scope but requires explicit user permissions. Can be fragile due to UI changes. Action name derived from UI element properties (e.g., title).
Carbon Event HotKey API	Register and query global hotkeys.	System-Wide / App Global	Largely legacy. Querying other apps' hotkeys is complex. Action name association is often indirect.
Shortcuts Framework (ShortcutsKit)	Manage automation workflows created in the Shortcuts app.	Automation Shortcuts	Relevant for shortcuts triggering user-created workflows. Action name is typically the Shortcut name. Doesn't cover traditional app shortcuts.

Relevant Learning Resource

While not directly demonstrating API usage for querying action names, understanding how users create custom shortcuts provides valuable context for where these mappings might originate. This video explains the user-facing process:

How to Create a Custom Keyboard Shortcut on macOS (via YouTube)

This process often involves associating a key combination with a specific menu command title, which reinforces the link between shortcuts and menu item names (`NSMenuItem.title`).

Recommended Workflow Strategy

Given the lack of a single API, a practical approach might involve these steps, depending on the target application and shortcut type:

Identify Context: Determine if you're targeting a specific application, a system-wide shortcut, or a user override.
Check Application Menus (AppKit): If targeting a specific Cocoa application, try inspecting its `NSMenu` structure first using AppKit APIs to find matching `NSMenuItem`s and their titles.
Query User Defaults: Check `NSUserDefaults` (global and application-specific domains) for `NSUserKeyEquivalents` to see if the shortcut has been customized by the user. If so, the dictionary key might be the action name (menu title).
Use Accessibility API: If the above methods fail or are insufficient (e.g., for non-standard apps or system-wide queries where the origin is unknown), use the Accessibility API (with user permission) to inspect the UI hierarchy for elements (like menu items) matching the shortcut and retrieve their descriptive text.
Consider Shortcuts Framework: If the shortcut might be related to the macOS Shortcuts app, explore the ShortcutsKit framework.
Handle Fallbacks: Accept that for some shortcuts, especially those triggering internal, non-menu actions or handled by legacy/non-standard methods, programmatically determining a user-friendly action name might not be feasible.

Limitations and Considerations

Permissions: Using the Accessibility API requires explicit user consent, which adds complexity to deployment and user experience.
Fragility: Relying on UI inspection (Accessibility, AppleScript) can break easily if application UIs are updated.
Incompleteness: Not all actions triggered by shortcuts correspond to visible menu items or user preferences (e.g., internal commands, shortcuts handled by background processes).
API Stability: Relying on undocumented aspects like the format of `NSUserKeyEquivalents` strings carries risk. Carbon APIs are legacy.
Sandboxing: App Sandboxing restrictions might limit the ability of your application to inspect other applications or read global preferences.