Objective-C has won the hearts of many developers. It started as a programming language that bundled object-oriented programming (OOP) with the likeness of the C programming language. Objective-C called NeXT and Apple home where it was the default programming language for NeXTSTEP, OS X, and iOS.
In 2010, Apple started developing Swift, a new programming language that would rival Objective-C in a few areas--specifically, type safety, security, and better on-hardware performance. Swift is more than 2.6x faster than Objective-C and more than 8.4x faster than Python. Swift 1.0 was released in September 2014.
From the cheat sheet:
HOW DOES SWIFT DIFFER FROM OBJECTIVE-C?
While Apple hasn’t announced plans to sunset the Objective-C language (in fact, Apple is still updating it), Swift is rapidly overtaking Objective-C to become more popular on Apple’s platforms.
Objective-C likely still has a long life, as Apple has yet to update its own Frameworks to be written in Swift. Until Swift 3.0, Apple will not be including the Swift runtime on iOS or OS X, leaving Xcode to package together the runtime into the iOS or OS X app to ensure binary compatibility.