I built my first iOS app in 2012 for a competition called 59 Days of Code. Back then the only way to build one was by collectively using Objective-C, UIKit, and optionally the Storyboard visual builder. I never became an expert at it since it wasn't something I wanted to do professionally — after all web technologies had always been my bread and butter. Nonetheless, I learned enough iOS development to get things working and eventually deploy an app to the AppStore. Since then the ecosystem has changed.