MacRuby notes series: code snippets in Xcode 4

If you use TextMate’s “code snippets” feature to insert commonly-used templates of Ruby code, you’ll be pleased to see that Xcode has a similar facility for MacRuby. It comes pre-populated with a variety of Objective-C snippets, but it’s easy to add your own Ruby snippets.

If you read my article on Beautiful standardized RDoc comments for your Ruby / Rails methods you’ll know that I’ve standardized on this method commenting pattern:

  # Provides a human-readable size of the attachment
  #
  # * *Args*    :
  #   - +precision+ -> the precision of the returned value, defaults to 1
  # * *Returns* :
  #   - a size value such as "5.1 KB"
  # * *Raises* :
  #   - +RuntimeError+ -> if the body is nil
  def human_size(precision=1)
    #...

In TextMate I use “rd <TAB>” to insert the comment snippet, and “defc ” to insert a commented blank method. In Xcode I do the same; here’s how.

1. Activate the right-hand Utilities drawer and in the bottom of it, click on the curly braces {} to activate the Code Snippet Library.
2. Type or paste in the code that you want to turn into a snippet; highlight it all.
3. Drag the highlighted code to the Snippet library. (It can be stubborn and not want to drag. Holding the mouse button down for a moment before dragging seems to help.)
4. Your snippet has been added to the Library; click once on the snippet and a callout window will show you the snippet and permit you to edit it.
5. Add your own descripton, completion shortcut, etc. Any text you surround with <# #> marks will be highlighted with a blue bubble for quick tabbing and substitution.

Here’s the full snippet.

    #
    #
    # * *Args*    :
    #   - ++ ->
    # * *Returns* :
    #   -
    # * *Raises* :
    #   - ++ ->
    #
    def

    end