I am interested in testing my current iPhone app against an older version of the SDK (3.1.3). I know that I can compile my code to run on this version of the SDK, but I want to test it to make sure it still works since I am using newer APIs and using weak linking so that it will continue to work on older iOS versions. Ever since upgraded Xcode to the latest version, iOS 3.1.3 is not an option to run in the iPhone Simulator. So I downloaded an older version of Xcode and installed it side-by-side my current version in the folder /Developer/Xcode Old. But when I try to compile my code and run it in the older version of Xcode, it chokes on the fact that the SDK doesn’t recognize the symbols for the newer classes – even though they are weak linked. Is there a way to get my app to run in the older SDK, so I can check that it’s working?
I have also tried to downgrade the iOS on my testing iPhone but it has not worked. Apple, I guess, makes it very hard to downgrade the iOS. And I’m not interested in jailbreaking my iPhone to allow me to downgrade it to allow me to test it. Why does Apple make it so hard to keep your apps compatible with older versions of the OS?
No. The libraries need to exist at link time; weak-linking just means they don’t need to exist at load (or lazy-load) time.
Compiling with an older “Base SDK” will also change what’s being compiled, since __IPHONE_OS_MAX_ALLOWED (or whatever it’s called) will be different. The analogous thing to do would be to compile against 4.0 but run that app in the 3.1.3 simulator, except that doesn’t work — Apple only fairly recently added backwards-compatibility into their simulator frameworks.
I’d just ask someone on 3.1.3 to test. It shouldn’t be too difficult to get an iPod Touch running 3.1.3, and there should still be plenty of users. If you’ve had any contact (email, twitter) with your users, that’s an option.