In some instances things might look quite weird to someone new to Cocoa in some cases, things seem almost too easy. Here is an example implementing a undo/redo functionality using Foundations’ NSUndoManager.

framework 'Foundation'
class Player
  attr_accessor :x, :y
 
  def initialize
    @x = @y = 0
  end
 
  def undo_manager
    @manager ||= NSUndoManager.alloc.init
  end
 
  def left
    undo_manager.prepareWithInvocationTarget(self).right
    @x -= 1
  end
 
  def right
    undo_manager.prepareWithInvocationTarget(self).left
    @x += 1
  end
end

Which you can use as such:

 
>> lara = Player.new
=> <Player:0x200267c80 @y=0 @x=0>
>> lara.undo_manager.canUndo
=> false # normal since we did not do anything yet
>> lara.left
=> -1
>> lara.x # -1
=> -1
>> lara.undo_manager.canUndo
=> true # now we can undo, so let's try
>> lara.undo_manager.undo # undo back to initial position
=> #<NSUndoManager:0x200257560>
>> lara.x
=> 0
>> lara.undo_manager.canUndo
=> false # we can't anymore which makes sense 
>> lara.undo_manager.canRedo
=> true # however we can redo what we just undone
>> lara.undo_manager.redo # redo to before we called undo
=> #<NSUndoManager:0x200257560>
>> lara.x
=> -1

The above example was tested in macirb but as you can see, actions can be undone and redone very very easily. This is just a quick preview of what you can do using Ruby + Cocoa and hopefully it will give you some cool ideas to implement.

During my free time, I’ve been reading, catching up on movies and TV shows and worked on the MacRuby book that I am writing for O’Reilly.

I wrote a bunch of small apps, played with various APIs and every single time I was amazed by all the goodies Apple makes available to developers. My most recent discovery is very simple but I wanted to share it with you.

I often type text in English, French and Spanish and I even mix the languages from time to time. SnowLeopard comes with a great spellchecker that auto detects the language I’m typing in and is most of the time correct. It’s a very impressive feature and I was wondering if, as a MacRuby developer, I could use one of Apple’s lib to detect what language is being used.  I dug through the documentation but didn’t find anything. I started looking at some header files and found the API to use

framework 'Foundation'
class String
  def language
    CFStringTokenizerCopyBestStringLanguage(self, CFRangeMake(0, self.size))
  end
end
 
puts "Bonne année!".language
# => "fr"
puts "Happy new year!".language
# => "en"
puts "¡Feliz año nuevo!".language
# => "es"
puts "Felice anno nuovo!".language
# => "it"
puts "أعياد سعيدة".language
# => "ar"
puts "明けましておめでとうございます。".language
# => "ja"

The documentation says that the result is not guaranteed to be accurate and that typically 200-400 characters are required to reliably guess the language of a string. (CFStringTokenizer Doc)

Probably not the most useful piece of code, but really cool none the less

Happy new year!