Since the introduction of Swift there are two important languages in the Apple ecosystem. Swift has become quiet popular in the meantime, so that it’s a good question whether you should still learn Objective-C or not.
The Swift and Objective-C interoperability is very good so that it is very easy to use both Swift and Objective-C in one project.
In iOS development you are using ARC almost all of the time. However, sometimes you have to disable ARC for Objective-C files.
The future belongs to Swift, but does this mean that you should migrate Objective-C code to Swift?
At the moment Apple has two major programming languages. So should you use Objective-C or Swift?
One of the biggest differences between Objective-C and Swift is the handling of nullability. But since Xcode 6.3 there are two new keywords in Objective-C that improve their interoperability: nullable and nunnull.
Since Xcode 7 there are so-called “Lightweight” Generics in Objective-C. The biggest benefit of this feature is a better interoperability between Objective-C and Swift.