How can I make a Mac App Store app check for updates?

Question

Within my app, how can I make it check if there is an update available in the Mac App Store, and tell the user about this?

As an example, Sparrow does this.

Answer 1

Charcoal Design has an open source component that does that: iVersion. But it requires you to add a file in your server for your application to read. Whenever you update the version, just change the information in your server, and iVersion will show the user that a new version is available.

You could also scrape Apple's servers to read the version of your app, but there is chance that your app may be rejected for doing that.