当键盘处于活动状态时，UIModalView会解雇陌生人

I'm having a strange issue with my modal view. The modal view asks for some user input so the keyboard pops on. When I click the cancel button to dismiss while the keyboard is still active they both dismiss in an animated fashion but the modal jerks to the right first, very strange. What would be my best course of action here? Would it be to disable my cancel modal button when the keyboard is active? If so how do I go about detecting the presents of the keyboard?I'm having a strange issue with my modal view.