Objective-C：各种iOS版本的编码

I was wondering whether it is possible / how it is possible to code a class so it can be run on different iOS versions in Objective-C. For example the VisualEffectView is only available in iOS8 and after. Is it possible to declare a VisualEffectView if iOS >= 8 and UIView if not? If so can this be done within a header file?I was wondering whether it is possible / how it