Is there a cable I can use to play my iPad on a iPhone speaker?

The iphone speaker i have has the same input as the ipad (the charging input), but it is inside a box shape that the width of the iPad will not fit into. I was hoping there was some sort of cable that i would be able to connect the ipad to the speaker, perhaps dual ended cable with the charging end?

Apple products are complete ***, you should get the Nexus 7.