ios-samples/BindingSample

MonoTouch BTouch Binding Sample

This example shows how we can utilize an existing Objective-C library and expose it for use in a MonoTouch project. For instance, you may have existing code written in Objective-C that you may want to bind to C# to consume in your MonoTouch project. This sample provides a basic template/overview of the steps involved, including:

• Creating a "fat" or multi-architecture library that can be target both the iOS simulator and device.

• Defining an API definition file in the form of a C# interface against the Objective-C API.

• Building a *.dll that contains both the binding and and the embedded native library.

##Understanding this Sample

This sample consists of three distinct source projects:

• Xcode Project in Objective-C
• MonoTouch Binding classes
• MonoTouch Sample Project

Please see the README in each project folder for more details.

##Building this Sample

To compile the Xcode Project and binding classes execute the make command from the root directory.

The make command will:

• Compile the Xcode Project for ARM6, ARM7, and Simulator
• Create a multi-architecture binary using lipo
• Create a *.dll in the binding folder using btouch-native

The resulting .dll is created using the LinkWithAttribute and will automatically embed the native library in your application.

##Creating a Universal Binary

A "fat" or multi-architecture library is a compiled binary that is usable on multiple targets, for example: armv6, armv7, i386 (simulator). In this sample we illustrate how to create a universal binary in two ways:

###Using lipo

Once we have built our library against the desired architectures we can create the universal binary via lipo. This will create a "universal" file from the architecture specific inputs we have provided. For instance:

lipo -create libXMBindingLibrarySample-armv7.a libXMBindingLibrarySample-armv6.a libXMBindingLibrarySample-i386.a -output 	libXMBindingLibrarySampleUniversal.a

Similarly, in our Makefile script we have lipo -create -output $@ $^ which will take the libraries compiled for armv6, armv7, and i386 using xbuild and output them to the current directory with the name of our build target.

###Using Xcode

In our Xcode project we have created a separate Build Target that will execute a post build Run Script to output a "universal" file.

This Run Script is also available for reference in the "Post-Build Run Script" group of the Xcode project.