RubyMotion is a toolchain that allows developers to develop native iOS applications using the Ruby programming language. RubyMotion acts as a compiler that interacts with the iOS SDK (Software Development Kit). This gives us enormous power to make use of Apple libraries; therefore, once the application has compiled and loaded, the device has no idea whether it's an application made using Objective-C or RubyMotion.
RubyMotion is a product of HipByte, founded by Laurent Sansonetti.
Laurent Sansonetti is a former Apple employee and the brain behind MacRuby. MacRuby is the implementation of Ruby on top of Mac OS X core technologies, which was maintained by Apple for over 4 years. And the best part is that RubyMotion is based on MacRuby.
While developing applications with RubyMotion using Ruby, you always have access to the iOS SDK classes. This gives you the benefit of even mixing Objective-C and Ruby code, as RubyMotion implements Ruby on top of the Objective-C runtime and iOS Foundation classes.
This is how a typical RubyMotion application works. The code written in RubyMotion is fully compiled into machine code, so the application created by RubyMotion is as fast as the one created using Objective-C.