In order to work with iOS applications inside of Mobile Test Workbench or create test ready applications you have to first build the iOS components inside of XCode. In the infocenter you can find the following information:
"Before you can test a mobile application, the application must first be instrumented. An instrumented application contains the application under test augmented with code that allows you to record or play back a test.
A native iOS application is a complete iOS project in Xcode. The build and compile process to instrument the application takes place entirely in Xcode on a Macintosh computer. One, single application is created for both recording and playback. "
In order to accomplish this right-click the iPhone environment inside of Worklight Studio and click Run-As->XCode project. Once the project is loaded inside of XCode please build/run the iOS components here. After these steps are completed you should be able to instrument the application correctly.
Here are some links to the infocenter for testing on iOS devices/simulators:
https://pic.dhe.ibm.com/infocenter/wrklight/v6r1m0/index.jsp?topic=%2Fcom.ibm.rational.test.lt.mob.wl.ditaval.doc%2Ftopics%2Ft_gsios_dev.html
https://pic.dhe.ibm.com/infocenter/wrklight/v6r1m0/topic/com.ibm.rational.test.lt.mob.wl.ditaval.doc/topics/t_test_ios_native_device.html
https://pic.dhe.ibm.com/infocenter/wrklight/v6r1m0/topic/com.ibm.rational.test.lt.mob.wl.ditaval.doc/topics/tinstall_iosapp_sim.html
For iOS you will also want to make sure you can successfully produce an ipa file with your certificates, app ids, and provisioning profiles. An easy way to test this is to attempt to archive your application inside of XCode using the Product->Archive menu option. If all of your build signing settings are correct this will complete successfully, but if it fails please investigate the errors that are displayed