Book Image

Reactive Programming with Swift 4

By : Navdeep Singh
Book Image

Reactive Programming with Swift 4

By: Navdeep Singh

Overview of this book

RxSwift belongs to a large family of Rx implementations in different programming languages that share almost identical syntax and semantics. Reactive approach will help you to write clean, cohesive, resilient, scalable, and maintainable code with highly configurable behavior. This book will introduce you to the world of reactive programming, primarily focusing on mobile platforms. It will tell how you can benefit from using RxSwift in your projects, existing or new. Further on, the book will demonstrate the unbelievable ease of configuring asynchronous behavior and other aspects of the app that are traditionally considered to be hard to implement and maintain. It will explain what Rx is made of, and how to switch to reactive way of thinking to get the most out of it. Also, test production code using RxTest and the red/ green approach. Finally, the book will dive into real-world recipes and show you how to build a real-world app by applying the reactive paradigm. By the end of the book, you’ll be able to build a reactive swift application by leveraging all the concepts this book takes you through.
Table of Contents (15 chapters)
Free Chapter
Migrating from Swift 3 to Swift 4
FRP Fundamentals, Terminology, and Basic Building Blocks
Set up RxSwift and Convert a Basic Login App to its RxSwift Counterpart
RxTest and Custom Rx Extensions – Testing with Rx
Schedule Your Tasks, Don't Queue!
Subscribe to Errors and Save Your App
Functional and Reactive App-Architecture

Concatenating and prefixing

While working with Observables, one of the most obvious requirements is to provide an initial or starting value to an observer. Some examples of this use case come into use while working with locations service and network connectivity when it becomes essential to provide an initial state to the observer; startWith is one such operator that allows us to prefix an initial value.

Let's work with its implementation in detail—startWith will prepend or add an Observable sequence to the beginning of the source Observable sequence, and those elements will be emitted before beginning to emit elements from the source Observable sequence.

The following describes the functionality of startWith:

Let's work with startWith in a code example, as follows:

In the playground that was set up in the previous section, remember to add the Helper file to...