.NET Development for the iPhone
Until recently your only choice for developing applications for Apple’s iPhone was to jump into the Apple development ecosystem. This means being willing to write Objective-C code in the XCode IDE. For many developers, learning Objective-C was seen as a huge barrier-to-entry. This is especially true for many .NET developers whom have never had to worry about memory management, pointers, and other C language responsibilities that they are unfamiliar with.
All this has changed with the introduction the MonoTouch framework, a part of Novell’s Mono Project. The Mono Project is an open-source implementation of Microsoft .NET Platform. It allows you to run .NET applications on nearly any platform, including Apple, FreeBSD, Linux, Unix, and others. MonoTouch, which is a new part of the Mono Project, allows you to write applications using C# with .NET platform that run on the iPhone.
The intent of this article is to provide a solid introduction to the MonoTouch platform, where to find all the necessary pieces, the limitations of it, and how to build a basic application.
How does it Work?
When building MonoTouch applications, most of the non-UI .NET 3.5 stack is either already available, or is in the roadmap to be included. This allows you to write applications using many of the .NET Framework Technologies that you’re already familiar with, including Windows Communication Framework (WCF), Workflow Foundation (WF), etc. It also includes nearly all of the Base Class Library (BCL) including things like Garbage Collection, Threading, Math Functions, System.Net, Cryptography, etc. For a list of available standard .NET assemblies see http://monotouch.net/Documentation/Assemblies. This is accomplished through a MonoTouch-specific set of base .NET libraries, similarly to how Silverlight and Moonlight work.
This means that you can compile standard .NET 3.5 code libraries using the MonoTouch core assemblies and use them in your application. So if, for example, you have a specialized library that does advanced math functions for engineering problems that you use for other applications, you can simply include the code library in your MonoTouch solution, and reference it. When you build your solution, it will compile it using the MonoTouch libraries, and it will then be available in your application.
MonoTouch also includes wrappers to the native iPhone APIs such as Location (GPS), the accelerometer, address book, etc. It also gives you the ability to bind to native Objective-C libraries that are not wrapped, so you can interop directly with existing Objective-C code.
How do I Distribute My Apps?
MonoTouch applications are distributed the exact same way that traditional iPhone applications are distributed, either via the Apple App Store, or Enterprise deployment.
The App Store is an online repository that allows users to pay for applications (if they’re not free), and download them. It is available from within iTunes, or directly from the iPhone itself. In order to get a license to distribute via the App Store, you must register with Apple, and pay $99/year.
Enterprise deployment is for those wishing to develop internal applications for a company, and distribute them to employees, etc., without listing them with the App Store.
What is the Licensing Model?
Unlike Mono, MonoTouch is not open source and is a commercial product. That means if you want to do anything useful with it you have to purchase a license. MonoTouch comes in three flavors and prices:
- Professional ($399) – A single personal developer license that allows you to develop applications and distribute them via the Apple App-Store.
- Enterprise ($999) – A single corporate developer license that allows you to develop applications and distribute via the App-store, or enterprise deployment.
- Enterprise, 5 Seat ($3,999) – The same as the Enterprise license, but includes 5 seats.
All three options include a year of free updates.
There is also an evaluation edition that allows you deploy to the simulator only. For the purposes of this introduction, that is all we’ll need.