Last year at WWDC 2012, Apple introduced Modern Objective-C alongside iOS 6. So what’s this? In a few words, it is a huge step forward to help developers write less code to achieve the same things. Worth mentioning is that modern Objective-C has nothing to do with iOS versions, it has to do with the compiler, which means that it is backward compatible.
Let’s dive into the basics of transitioning to modern Objective-C. Xcode offers a refactoring tool (edit>Refactor>Convert to Modern Objective-C syntax) which will convert your project to modern objective-c (it will also set the appropriate flag in build settings). If you would like to adopt modern Objective-C when writing your code, which is the best, as it is intended to help you write less lines of code, general rules for doing so are the following.