[Presented at the joint meeting of CocoaHeads-NYC and the New York FileMaker Developers Group, July 8, 2010. I've heavily edited this since giving the presentation. The original text was much more sparse.]

The notes below are online.

Mixed audience for this meeting

Therefore:

• Partly an intro to global hotkeys
• Partly a glimpse into Cocoa development, for newcomers
• Will show two apps, one trivial and one more advanced

App One: "Hello World" of hot keys

App is called "Hotness".

• A minimal complete app
• Bare-bones UI with five buttons (actually a matrix of five button cells)
• Just one Objective-C class, four methods
• Hotkey actions are defined in five AppleScript files
• Uses a third-party library called DDHotKey which makes registering hotkeys very simple

Cocoa patterns and techniques:

• target-action (the button matrix has a target)
• delegation (the application object has a delegate)
• calling AppleScript from Cocoa
• bringing your application to the front (see the hotkey mapping for Control-0)

App Two: more realistic

App is called "WhatKeys".

• User can create, modify, and remove hotkey assignments
• Hotkeys can be mapped to either an AppleScript file or AppleScript code entered directly
• Like Hotness, uses DDHotKey
• Uses a third-party library called ShortcutRecorder for entering and displaying keyboard shortcuts

Cocoa patterns and techniques are same as in Hotness, plus:

• MVC ("Model-View-Controller")
  • a model class (WKHotKeyAssignment)
  • view controller and window controller ("coordinating controllers")
  • array controller ("mediating controller")
• bindings
• properties
• responder chain
• user defaults and property lists (for saving the user's hotkey assignments)
• handling NSError

Where to get

Here are links for the source:

• Hotness
• WhatKeys

To compile the example code you'll need Apple's Developer Tools, which you can get for free here (requires registration). After installing the Dev Tools, double-click an xcodeproj file to open the project in Xcode.