At the core of game development is your game's code. It is the brain of your project and outside of the art, sound, and various asset developments. It is where you will spend most of your time creating and testing your game. Up until Apple's Worldwide Developers Conference WWDC14 in June of 2014, the code of choice for iOS game and app development was Objective-C. At WWDC14, a new and faster programming language, Swift, was announced and is now the recommended language for all current and future iOS games and general app creation.
As of the time of writing, you can still use Objective-C to design your games, but programmers, both, new and seasoned, will see why writing in Swift is not only easier for expressing your game's logic, but even more preformat. Keeping your game running at that critical 60 fps is dependent on fast code and logic. Engineers at Apple developed the Swift programming language from the ground up with performance and readability in mind, so this language can execute certain code iterations faster than Objective-C while also keeping code ambiguity to a minimum. Swift also uses many of the methodologies and syntaxes found in more modern languages, such as Scala, JavaScript, Ruby, and Python.