... around 30% of iOS devices today arerunning iOS versions that are about a year or a year and a half old. If today we areworking with iOS 5, there are still iOS devices out there running iOS, 3 for ... runs on iOS 5 out to the App Store.Some of the classes that we use are available only on specific versions of iOS. For in-stance, the NSJSONSerialization class is available only in iOS 5 SDK ... available only in iOS 5 SDK and only devicesrunning iOS 5 will be able to run such code. However, if you are planning to support iOS 4 as well as iOS 5, then you can, at run-time, detect the availability...