I was trawling through the App Store the other day when I noticed something worrying. Over half of the apps I wanted to download no longer work after the iOS 4 update.We're not talking two-bit, bedroom-cooked apps here; I'm talking about big titles from big software houses.So why has this happened? Because backwards compatibility isn't something Apple seems to worry about. Just look at all those iPod docks that are rotting slowly in Silicon Cemetery.We've slagged off Windows for decades for suddenly not supporting software we paid good money for, and we shouldn't be any more lenient with Apple. I don't want to have to check for anything marked "compatibility issues"; I just want to download an app in complete confidence that it'll work.This isn't like the Android Market, where certain apps will only work with certain combinations of OS version and handset – not a great situation for the Android movement, but kind of understandable with an open-source OS and so many manufacturers using different versions on varying hardware. With the App Store, Apple is the only hardware manufacturer involved.Yes, absolutely the developers need to update and support their software, but it seems Apple's secretive stance, while being a brilliant hype machine, is a stumbling block to achieving a smooth evolution. The developers don't appear to be given enough warning of upgrades to keep up.Ignoring the past while inventing the future may have helped Apple rip up the rule books in recent years, but this is one area where I'd rather they weren't so cavalier.