Q & A with Clay Allsopp, author of RubyMotion

Q. Why did you write RubyMotion?

A. There are so many developers who want to write iOS apps but are stymied at the idea of learning Objective-C, a very different language from Ruby. With RubyMotion, learning the nuances of Objective-C is no longer a requirement for developing for the iOS platform! I wanted to write a guide to help these developers become familiar with the iOS SDK and quickly get started on the right foot.

Q. How much Ruby knowledge do I need for the book?

A. You need some Ruby experience, as the book jumps right into the iOS SDK without delay. But don’t worry! Only familiarity with how standard object-oriented development (classes, inheritance, etc) works in Ruby is necessary. We do use some Ruby tricks here and there, like ‘instance_variable_get’, but they are explained and easy to pick up.

Q. What is your favorite RubyMotion feature?

A. The workflow is much more lightweight than the usual Xcode-centric development process. All of the tools are command-line based, from building your apps, to sending it over TestFlight, to running automated tests. I can work with the tools familiar to me (Rake, RubyGems, continuous integration) and end up with exactly the same result without compromising app quality.

Q. Would RubyMotion be helpful if I already know Objective-C?

A. Yes, because the RubyMotion community is working to push the core ideas of iOS and mobile development in new directions. The Ruby community has always had a propensity for crafting DSLs and new abstractions, and those efforts have carried over to RubyMotion. Projects like ProMotion and Formotion have no parallels in Objective-C iOS development, and they could be a real boon to your next project.

Q. Do you discuss third-party RubyMotion libraries in the book?

A. Yes, we use the popular BubbleWrap library several times and show how a few others (like TeaCup and Formotion) could speed up development.

Q. Will I be able to build a working iOS app of my own after reading this book?

A. Yes! The last chapter builds a complete API-based app from scratch, which is an incredibly common task for many developers. But even before the end, you’ll be familiar with the most typical interface components and patterns and should be comfortable jumping into any new projects.

Developers interested in native iOS app development have been restricted to the limits of Objective-C and Xcode--until RubyMotion came along. RubyMotion enables you do full iOS development using Ruby. You have access to familiar tools such as Rake and RubyGems and can compile Ruby code into native applications. RubyMotion even comes with a Ruby console useful for live coding and interactive debugging. And since RubyMotion is built on top of the Objective-C runtime, you can use all of Apple's libraries and most third-party code alongside Ruby classes.

This book takes you from zero knowledge of iOS development to building an app that displays information about colors using a web service API. You’ll work through each topic with a small example app that covers just enough to get you familiar with the techniques you need to get real work done.

You'll start with just drawing boxes on the screen, but you'll quickly add animations, a navigation stack, and high-performance table views. You’ll peek into less visible components, such as using Ruby metaprogramming to create JSON-based models. You'll use some incredibly useful common Ruby techniques that are only possible in RubyMotion, such as writing automated unit tests with an RSpec-like framework.

Using both Apple's existing libraries and fresh, community-driven RubyMotion projects, you'll be well on your way to writing real-world apps.