iphone semaphore problem or other synchronization

hi everyone,
when I used thread synchronization in mac program, use the MPSemaphoreID that in CarbonCore.framework, but I can't find it in iPhoneOS2.0.sdk, instead it is at iPhoneSimulator2.0.sdk. why? If someone can give some advice for thread synchronization? or maybe some others instead of, thank you very much for your reply.