RubyMotion iOS Development Essentials: Forget the complexity of developing iOS applications with Objective-C; with this hands-on guide you'll soon be embracing the logic and versatility of RubyMotion. From installation to development to testing, all the essentials are here.

This is the most standard way to build your application, by interacting with Apple APIs and writing apps in Objective-C. Applications made using native Apple APIs can use all possible device capabilities, and are relatively more reliable and high performing (however, the topic of performance is debatable based on the quality of the developer's code).

Mobile web applications are simple web applications extended for mobile web browsers, which can be created using standard web technologies such as HTML5. For example, if we browse through http://www.twitter.com in a mobile browser, it will be redirected to http://mobile.twitter.com, which renders its corresponding views for mobile devices. These applications are easy to create but the downside is that they have limited access to user data (for example, phonebook) and hardware (for example, camera).

These applications are somewhere in between mobile web apps and native applications. They are created using common web technologies such as HTML5 and JavaScript and have the ability to use device capabilities via their homegrown APIs. Some of the popular hybrid frameworks include Rhomobile and Phonegap.

If we compare the speed of development and user experience, it can be summed up with the following diagrams:

From the preceding diagrams we see that mobile web apps can be created very quickly but we have to compromise on user experience. While native apps using Objective-C have good user experience, they have a very steep initial learning curve for web developers.

RubyMotion is good news for both users and developers. Users get an amazing experience of a native application and developers are able to develop applications rapidly in comparison to applications developed using Objective-C. Let's now learn about RubyMotion.

For a newbie developer, Objective-C is an arduous affair. It's complicated to code; even for doing a simple thing, we have to write many lines of code. Though it is a powerful language and one of the best object-oriented ones available, it is time consuming and the learning curve is very steep. On the other hand, Ruby is more expressive, simple, and productive in comparison to Objective-C. Because of its simplicity, developers can shift their focus onto problem solving rather than spending time on trivial stuff, which is taken care by Ruby itself. In short, we can say RubyMotion allows us to use the power of Objective-C with the simplicity of Ruby.

Ruby classes used in RubyMotion are inherited from Objective-C classes. If you are familiar with the concept of object-oriented programming, you can understand its power. This means we can directly use Apple iOS SDK classes from your RubyMotion code. We will be discussing more on this in the next chapter.

RubyMotion apps get direct access to iOS SDK APIs, which means the size of application and performance created using RubyMotion is comparable to the one created using Objective-C. It implements Ruby on top of the Objective-C runtime and iOS Foundation classes. RubyMotion uses a state-of-the-art static compiler based on Low Level Virtual Machine (LLVM), which converts the Ruby source code into a blazing fast machine code. The original source code is never present in the application bundle. A typical application weighs less than 1 MB, but the size can increase depending on the use case.

One of the key features of RubyMotion is that it takes care of memory management. Just like ARC (Automatic Reference Counting) with Xcode 4.4 and above, we don't have to take the pain of releasing the memory once an object is no longer used. RubyMotion does the magic and we don't need to think about it. It handles it on its own.

RubyMotion has a terminal-based workflow; from creation of the application to deployment, everything can be done through terminals. If you are used to working on terminals, you know it adds to speedier development.

The terminal window where you run Rake also gives you the option to debug with REPL (Read Evaluate Print Loop), which lets you use Ruby expressions that are evaluated on the spot, and the results are reflected on the simulator while the application is still running. The ability to make live changes to the user interface and internal application data structures at runtime is extremely useful for testing and troubleshooting issues with the application, as this saves a lot of time and is much faster than a traditional edit-compile-run loop. If this confuses you right now, don't worry, as we will discuss more on this powerful feature in later chapters.

We can use RubyMotion salted gems easily by just adding them in the Rakefile. What are RubyMotion salted gems? We can't use all the gems that are available for Ruby right now, but there are a lot of gems specifically developed for RubyMotion. As the RubyMotion developer community expands, so will its gem bouquet, and this will make our application development rapid.

Third-party Objective-C libraries can be easily used in a RubyMotion project. It supports CocoaPods, which is a dependency manager for Objective-C libraries, making this process a bit easier.

RubyMotion has a console-based inbuilt interactive debugger for troubleshooting the issues both on a simulator and on a device using GDB (GNU Debugger). GDB is extremely powerful on its own, and RubyMotion uses it for debugging the compiled Ruby code. Also, RubyMotion projects are fit for Test Driven Development (TDD). We can write a unit test for our code from the beginning. We can use Behavior Driven Development (BDD) with RubyMotion, which is integrated into every project. We will discuss more about testing in later chapters.

RubyMotion installation is really simple and takes no time at all. RubyMotion is a commercial product that you need to purchase from www.rubymotion.com. Once purchased, you will receive your unique license key and installer.

RubyMotion installation is a five-step procedure and is given here:

RubyMotion is a fast-moving framework and we need to upgrade it once there is a new release available. Upgrading RubyMotion is again really simple—with one command, you can easily upgrade it to the latest version.

sudo motion update

You need to be connected to the Internet for an upgrade to happen.

sudo motion update –force-version=1.2

Now that we have installed our RubyMotion copy, it's good practice to confirm which version we have installed; to do this, go to the terminal and run the following:

motion –v

This command outputs the RubyMotion version installed on your machine. If you get an error, you need to reinstall.

With RubyMotion, you are not forced to use Xcode. As every developer is more comfortable with a specific editor, you are open to choose what you like. However, we recommend the following editors for Ruby development:

If you are facing some issues, the preferred way to get a solution is to discuss it at the RubyMotion Google group, (https://groups.google.com/forum/?fromgroups#!forum/rubymotion), where you can interact with fellow developers from the community and get a speedy resolution.

Sometimes you might not get a precise response from the RubyMotion group. Not to worry, RubyMotion support is there to rescue you. If you have a feature request, an issue, or simply want to ask a question, you can log a support ticket—that too from the command line using the following command:

$ motion support

This will open up a new window in your browser. You can fill and submit the form with your query. Your RubyMotion license key, email address, and environment details will be added automatically.