A little over a year ago, I started working full time as iOS developer for a mining company. One of the first projects is create spreadsheet like application on iPad. At that time there is no UICollectionView, and I found GMGridView to be interesting. I did look at an existing product called iOS Data Grid Table but there are two limitations which prevents me from using it: 1) It displays the values only (read only); 2) Perhaps more important, at that time I don’t recall it includes source code. So I ends up creating my own spreadsheet like tables based on GMGridView. I also read the nice work done by Tom Thompson. Of course that time my knowledge on UITextField (and UITableView for that matter) is not very good, and I did not understand all good work he did. I did used the UIPicker in my project, as it helps the user input data in many cases (simplify/ease input, reduce validation), I believe I borrow some idea from RayWenderlich’s tutorial too (UIPopupController and UIPicker).
A year and half later, when I took another look at this thing, I found at least four new things which are interesting, the shinobi controls (commerical), the MDSpeadView (looks like read only, github, open source), nucliOS (by Infragistics, commercial) and UICollectionView (Apple iOS native, tutorial by RayWenderlich.com)