how can i get object from tag?

i have one view .in th开发者_StackOverflow社区at view i have 2 buttons .

i know tag of that button . i want to change image of that button.

how can i change image by this tag?

UIButton *button = (UIButton *)[myView viewWithTag:myTag];
[button setImage:... forState:...];

UIScrollView * scView=(UIScrollView*)[self.view viewWithTag:20];
UIButton *button = (UIButton *)[scView viewWithTag:3];