Running SenTestingKit unit tests in Instruments

This answer begins with SenTest for OS X. If you are concerned with using SenTest for iOS under instruments, skip to the next section.

OS X Unit Tests in Instruments

I realize this is a bit late, but I needed to run instruments on a logic test today and got it working for my environment, so here's what I did:

1. With Instruments running, create a new document.
2. Choose Target from the Target drop down in the document
3. Check the "Traverse Packages" option in the lower-right to allow you to dig inside of the Xcode package
4. Navigate into /Applications/Xcode and find the otest binary inside of /Applications/Xcode.app/Contents/Developer/Tools/ and select it
5. Add OBCJ_DISABLE_GC with a value of YES as an environment variable (don't do this if you're running GC)
6. Add DYLD_FRAMEWORK_PATH and point at the directory containing of your .octest package
7. Add DYLD_LIBRARY_PATH with the same value as DYLD_FRAMEWORK_PATH
8. Set your Working Directory to be the directory where your .xcodeproj lives
9. For arguments, use -SenTest Self and the full path to your .octest package

Some of the environment variables and your working directory may not be essential depending on whether you need additional frameworks to load and whether you have test files in your code directory that require reading. So, you may omit those steps if they don't apply to you.

Once you're done, you'll be able to Save the document and use it to run the tests.

iOS Unit Tests in Instruments

After the OP clarified the requirements, I went about verifying the basic instructions for this with an iOS-simulator-based project.

For iOS, you need a somewhat different configuration, owing to the fact that you're debugging a different executable, and you will need different libraries. So, the DYLD_FRAMEWORK_PATH will include both the path to your .octest package's directory, and that of the Simulator's Frameworks. The latter will be something like this:/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.0.sdk/Developer/Library/Frameworksdepending on which version of the simulator you are using and we'll refer to it below as SDKPATH

1. With Instruments running, create a new document.
2. Choose Target from the Target drop down in the document
3. Check the "Traverse Packages" option in the lower-right to allow you to dig inside of the Xcode package
4. Navigate into /Applications/Xcode and find the otest binary inside of /Applications/Xcode/Developer/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.0.sdk/Developer/usr/bin/ and select it
5. Add DYLD_LIBRARY_PATH and point at the directory containing of your .octest package
6. Add DYLD_ROOT_PATH pointed just at the SDKPATH (above)
7. Add IPHONE_SIMULATOR_ROOT with SDKPATH (above)
8. Add DYLD_FRAMEWORK_PATH and point at the directory containing of your .octest package and the SDKPATH (above), separating them by a colon (:) in the path list
9. Add CFFIXED_USER_HOME with your iPhone simulator home (~/Library/Application Support/iPhone Simulator although I've expanded it before putting it here, as I'm not sure the ~ gets interpreted)
10. Set your Working Directory to be the directory where your .xcodeproj lives
11. For arguments, use -SenTest Self and the full path to your .octest package

Heres another way to do this thats far simpler and allows greater control over what you profile:

Put a breakpoint at the start of setUp and run the test you want to run. When Xcode hits the breakpoint, open Instruments and search for octest under targets. Then you can simply attach to that process. Switch to Xcode and continue running after your breakpoint and instruments should profile all the tests you wanted to run.

Hope this helps.