Xcode's Interface Builder is a pretty good user-interface layout tool, especially for simple situations. However, it is not the best tool for every job. Sometimes you have to write code to dynamically create user interface elements or to move them around as the view is resized.
When you do this, you find that iOS doesn't help you much beyond some rudimentary autoresizing options. While iOS 5 does provide some autolayout features, they are limited, and they don't help at all if you need to support earlier versions of iOS.
I also couldn't find any third-party implementations. I found a few posts and samples for making a grid-like
UITableView, but I wanted a way to lay out things in a grid in a plain-old
So I decided to write my own grid-layout thingees for iOS.