One of the new features of macOS Mojave which was placed fairly close to the top of the list was Quick Actions, which Apple promised let the user work on files directly in the Finder. These allow us to rotate images, create PDFs, and more without having to open an app. In this series of articles, I’m going to look more deeply at Quick Actions: what they are, how you can make and control them, and where they take macOS.

Quick Actions aren’t exactly new, and are part of a family of add-ons listed in the Extensions pane in System Preferences. This is a confusing jumble of quite disparate components and features which merits explanation.

Actions are services offered by installed apps. Standard is Markup, which lets you mark up PDF and image documents using features bundled in macOS. A few third party apps add their own services, such as Pixelmator’s Repair Tool, but these are generally uncommon.

Finder Extensions are tools which have been built to add services to the Finder’s contextual menu, such as Objective-See’s WhatsYourSign. Again, these are generally uncommon.

Photos Editing items are services provided by apps which process images or video, normally including Markup, which can be used within the Photos app. Some third-party apps like Affinity Photo offer several.

Share Menu items are extensions which are included in sharing options, including AirDrop and Messages, which makes them something of an odd man out. A few apps supplement the standard suite which comes with Mojave, but these are in general quite different from other extensions controlled here. They may be stored in the Sharing folder in ~/Library, but bundled services are stored as appex bundles in the PlugIns folder inside the FinderKit private framework, and possibly elsewhere.

Today is another anomalous category: these are widgets which will be displayed in the Today half of the Notification Centre, accessed from the icon at the far right of the menubar. They get updated information or perform a quick task.

Finder items are those now known as Quick Actions, which includes Markup, also listed in Actions and Photos Editing. Users generally install these in ~/Library/Services, but most are provided as appex bundles elsewhere. These are the focus of the articles in this series.

All claims to list all third-party extensions, which you might think is the combination of all items in the other categories, only it isn’t. Instead, it’s a listing of third-party apps which provide extension services which are listed in other sections, and doesn’t include those which are built in, like Markup, or any Automator Quick Actions which you have added yourself. The advantage of this list is that it helps you enable all the extensions provided by specific apps.

It’s worth pointing out that Apple here uses the term extensions quite differently from its more general use in macOS. Normally, extensions refers to kernel extensions, which are low-down software modules to extend the kernel’s features and functions, and are contained in the Extensions folders in /System/Library and /Library. You won’t find any of the extensions listed in the Extensions pane in those folders: instead they give high-level user access to app features.

Quick Actions are most obviously accessed through the new toolbar which is displayed below an item’s metadata in Finder column and gallery views. They are also available in the Finder’s contextual menu, where they can appear in both the Quick Actions list and in Services. This is where they can become confusing.

Select a file and its available Quick Actions are shown in both column and gallery views, and they are listed in its Quick Actions menu item. Select a folder and its available Quick Actions are only shown in gallery views (as the contents of the folder are shown in column views), but in both the Quick Actions and Services items in the Finder’s contextual menu.

Most of the items listed in the Extensions pane aren’t delivered by code stored in Services or Shared folders in Libraries, but in app extension bundles with the extension .appex in the PlugIns folder inside various installed apps. This is true, for example, for the Photos Editing extensions provided by Affinity Photo.

The bundled Quick Actions of Create PDF, Markup, Rotate and Trim are implemented using placeholder plugins in the Finder app itself, which presumably call services provided by private frameworks.

Apple’s developer guide to app extensions is here, but is now archived and hasn’t been updated since well before Mojave. It therefore doesn’t mention Quick Actions, and Apple doesn’t appear to have published any successor documentation.