Question

Since the launch of IOS 5, I have had to make some changes to my app that only apply when IOS 5 is being used. How can I tell when launching my app whther the user is using IOS 5 or IOS 4 or earlier?

Answer 1

You should probably avoid asking about the system version altogether.

A better design would ask about a specific feature.

For instance: if (NSClassFromString(@"UIPrintInfo")) would tell you if the current device supports the printing API,available in 4.2 or higher.

That way you can plan your code to use a feature if it’s available, on not based on the OS version. More on this here – How to check iOS version?

But if you must then –

float version = [[[UIDevice currentDevice] systemVersion] floatValue];