如何从非ui线程/函数强制UIScrollView的屏幕更新(iPhone)

I am drawing a set of images on the uiscrollview from a non-ui thread/function. But its only displayed after all the images are done drawing. For drawing all the images, I have written a function and that is what is being called as the non-ui thread. I did write this line inside the functionI am drawing a set of images on the uiscrollvie