Objective-C Fundamentals

Mono (.NET)
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the iOS platform. For a while, this caused Adobe to discontinue the Packager for
iPhone component of CS5, and the future remained uncertain for a number of alternative
development tools (such as Corona and Rhode). All of these tools were arguably
creating applications that “link to Documented APIs through an intermediary
translation or compatibility layer or tool” and, for the most part, weren’t written in C,
C++, or Objective-C.
The whole war of words between Adobe and Apple can perhaps be best summed
up with the following excerpt from an Apple press release dated September 9, 2010
(www.apple.com/pr/library/2010/09/09statement.html), in which Apple sought to
clarify the terms of the license agreement and its intent behind the changes:
We are continually trying to make the App Store even better. We have listened to our
developers and taken much of their feedback to heart. Based on their input, today we are
making some important changes to our iOS Developer Program license in sections 3.3.1,
3.3.2 and 3.3.9 to relax some restrictions we put in place earlier this year.
In particular, we are relaxing all restrictions on the development tools used to create iOS
apps, as long as the resulting apps do not download any code. This should give developers
the flexibility they want, while preserving the security we need.
One interesting side note about the Packager for iPhone is that it’s designed to work
on a Windows-based PC, meaning users don’t need to purchase a Mac to develop
iPhone applications. The Flash toolchain can produce iPhone applications ready for
deployment to a device or submission to the iTunes App Store. Developers still are
required to purchase a yearly subscription to the iPhone Developer program in order
to obtain the code-signing certificates required.
C.6 Mono (.NET)
Developers familiar with the Microsoft .NET development platform may have heard of
the Mono open source project, produced by Xamarin (previously Novell). The Mono
project aims to deliver a compatible .NET CLR runtime environment and development
tools for environments not supported by Microsoft’s own implementation (primarily
various Linux- and UNIX-based systems, such as Mac OS X).
By reutilizing a number of key Mono technologies, Xamarin has created a .NET
runtime environment that can run .NET applications on iOS-powered devices. This
means that a developer can use Visual Studio (or Xamarin’s MonoDevelop IDE) to
develop C# applications that can be deployed to iPhones. You still enjoy most of the
comforts of .NET, such as a garbage collector and an extensive set of base class libraries.
MonoTouch works in a fashion similar to Adobe’s Flash solution. Because iOS
doesn’t support runtime environments that require just-in-time (JIT) compilation,
MonoTouch contains a compiler that’s capable of ahead-of-time (AOT) compilation.
This turns Common Intermediate Language (CIL)-based assemblies into native ARM
code at compile time rather than performing this process each time the application
starts. One limitation is that a few base class library APIs, such as System.Reflection.Emit