I published app to appstore and to my bad luck it was rejected.The reason is:
 - Was not optimized to support the device screen size and resolution;
Various visual elements were out of place in some views on iPad.

I do not understand what does this mean ?

Im running it in iphone 6.0,iphones5.0 simulators,iphone retina(3.5 inch),iphone retina(4 inch),ipad ,ipad retina.It is fine and I dont find any issues with resolution part.
I couldn't understand in which mode they did it.

How can I make my app to run well in both iPad and iPhone.Do I have to make any screen changes/resolutions.