在ios中为标签制作摇晃效果？

Am working with shake effect for label i called the animation while pressing cell in tableview but it is not working.if i call animation in cellForRowAtIndexPath:(NSIndexPath *)indexPath it is working but if i cal it in didSelectRowAtIndexPath:(NSIndexPath *)indexPath it is not working. could any one help me??? thanks in advanceAm working with shake effect for label i called