Add support for setting the specific toolchain

[paxswill]

For example, I have Xcode 3.2.6, Xcode 4.0, and Xcode 4.2 on our Jenkins machine. Most projects should be built against the latest version, but some are incompatible, so we would like them to build against a specific toolchain. This can be done by exporting the DEVELOPER_DIR environment variable before running xcodebuild (documentation for this is in the man page for xcrun). I see this as a similar setup to the JDK/Git/Ant/Maven setup, how you can select either the default or a specific version for a job.

[bbiallowons]

You're able to set environment variables before building with the following plugin:

https://wiki.jenkins-ci.org/display/JENKINS/Setenv+Plugin

This is not the best solution for every use case atm, think of a bigger CI-System with a more complex build cluster (2 nodes or more). With this solution, you've to make sure, that every node has every SDK installed (or your build will fail).
To solve this issue, JDK/Git/Ant/Maven are using an automatic tool installation. This is also possible with Xcode, but there're some things to consider:

1. Xcode is not free available, so we've to
   1.1. support for an onsite infrastructure, where we can fetch the required Xcode SDK
   1.2. support for storing Xcode SDKs to Jenkins master node to distribute from there
2. We've to add support for getting information which SDKs are available and where to fetch
3. Downloading >3.5GB and installation of this SDK takes a little time (smaller issue, but often more than 10min)
   ...

So, this is not a trivial step, but were're working on a solution for that. I hope, the use of the SetEnv-Plugin could temporarily help you with your setup.