I’ve created a widget to pull traffic data from the excellent Gauges service by GitHub and display it in your Status Board. If you haven’t heard of Status Board yet, it’s a dashboard for showing all sorts of data on your iPad (or big screen TV) developed by Panic, Inc.

• View on GitHub
• View more widgets at Status Board Widgets

While working on creating the distribution script for packaging the Singly iOS SDK, I ran into a number of issues trying to automatically assign a custom icon to one of the distributed folders. I searched and found a myriad of solutions, but they all suffered from one or more problems:

• the embedded icon was not high-resolution, so it looked terrible when scaled,
• or you could not use an ICNS bundle directly without extracting an image from it,
• or most of the command examples did not function properly on Mountain Lion.

So after much trial and error, I finally came up with a solution that would address all of the above issues.  The following assumes that you already have an ICNS bundle containing your icon at various resolutions.

Step 1 — Create Folder w/Custom Icon

The first thing we need to do is create a temporary folder in Finder and set our ICNS bundle as its icon via Finder’s Inspector:

• Create a new folder (for this example we’ll use “tempfolder” as the name) in Finder.
• Right-click on the folder and select “Get Info” from the context menu.
• Drag your icon file and drop it onto the standard blue folder icon at the top left of the Inspector window.

Step 2 — Extract the Icon Resource

Now that we have a folder with our custom icon set correctly, we will need to extract the resource fork containing our icon. Open the Terminal and execute the following command:

DeRez -only icns path/to/tempfolder/$'Icon\r' > MyIcon.rsrc

This will extract the properly formatted icon resource into a separate file that we will use later.  You can now trash the temporary folder we created in step 1.

Step 3 — Apply the Icon Resource

Once we have the extracted resource file, we can apply it to any folder (or file) of our choosing at anytime from the command-line (or a script). This is useful if you need to automate the process of setting a custom icon on a generated folder, such as when you are packaging a new release.

To apply the custom icon to your folder, execute the following in Terminal (or from a script):

Rez -append path/to/MyIcon.rsrc -o path/to/folder/$'Icon\r'
SetFile -a C path/to/folder

That’s it!

Be sure to keep your extracted resource file around so you can use it in the future.

A simple convenience function for adding together an array of numbers.

//
// Iterates over an array of numbers and returns the sum. Example:
//
//   _.sum([1, 2, 3]) => 6
//
_.sum = function(obj) {
  if (!$.isArray(obj) || obj.length == 0) return 0;
  return _.reduce(obj, function(sum, n) {
    return sum += n;
  });
}

View the Gist