Reactive iOS Development with RxSwift

Abstract

Over the last decade, demand for reactive and scalable mobile applications has massively expanded. Reading developer news about scalable applications certainly brings up the benefits of Reactive Extensions (Rx). RxSwift library, which is part of the larger Rx family, allows using Swift in an entirely new way. Writing rather difficult asynchronous code in Swift becomes more straightforward using RxSwift. This study aims to explain the architectural concepts of reactive programming in iOS development. This study also proposes the usage of RxSwift combined with Model- View-ViewModel (MVVM) design pattern to create robust iOS applications. In addition, the study offers an alternative way of building user interfaces without iOS Storyboards. During the study, an iOS application was developed with Swift emphasizing the usage of RxSwift with MVVM design pattern. The resulting application fetches cryptocurrency data from CoinGecko Application Programming Interface (API) and presents the data using graphs. A real-time WebSocket chat was also created to showcase reactive methodologies. User interface for the application was built with UIKit using SnapKit to provide autolayout capabilities. Created exclusively for the study, the application is not released to the App Store nor is the source code publicly available. The study revealed that while RxSwift is an excellent choice for skilled developers, high learning curve and the needed knowledge of the Swift programming language can be challenging. Also, the possibility of introducing strong reference cycles and misbehaving streams can be challenging to debug.