How have iOS Development Technologies Changed over Time? A Study in Open-Source

iOS development has undergone a significant shift related to the introduction of the Swift programming language, conceived to replace or complement Objective-C. This may have impacted how iOS apps are developed, e.g., concerning User Interfaces (UI). This study investigates current trends in iOS app development, focusing on programming language preferences and UI framework adoption, by examining 140 open-source native iOS applications. The results indicate that $94 \%$ of the apps now integrate Swift code, showcasing its widespread acceptance since its 2014 inception, and also show different migration patterns. The paper also compares the established UIKit, a popular framework for building iOS user interfaces, with the recently introduced SwiftUI, which was introduced in 2019. Our analysis shows a strong uptake of SwiftUI, used in 64 of the apps in our dataset. Notably, for apps initiated after the introduction of SwiftUI, almost half were developed with SwiftUI from the start. CCS CONCEPTS - Software and its engineering $\rightarrow$ Empirical software validation; Programming languages; Mobile application development; Programming languages.