Match XCode compile errors to deployment target iOS 5.1-Collection of common programming errors

No, it is your responsibility to check availability of classes, methods, constants and enumerations at runtime, when there is a chance that your deployment target doesn’t have them.

if ([MyClass class] == nil) { }

if (![MyClass instancesRespondToSelector:@selector(foo)]) { }

if (&kSomeConstant == NULL) { }

Also, if a whole framework may not exist, link to it optionally (weak). Finally, test on real devices with every OS version you support.

Old versions of Xcode are available to install side by side, but they will fail to build your project if you used any iOS 6 frameworks, classes, methods, etc.