How can I pass two value to a NSThread object from the main thread OR have the same value in both threads?

Question

I have a function which executes as a different thread, thread named imageThread. But when the device rotates, the control automatically returns to the main thread and after their execution its given back to the imageThread. That's how i wanted it to function. But the problem is I am using some global variables, whose value changes in the mainThread but the imageThread is still having the old values when it get the control back. How can I make those values retain same in all the threads as the same?