Update DAKeyboardControl.m

[hotdang-ca]

Fixes an issue where we attempt to get self.keyboardActiveInput.inputAccessoryView, but the target doesn't respond to this request, resulting in a crash. Example case is presenting an MFMailComposeViewController. Can be recreated by creating a new application, integrating the project, presenting an MFMailComposeViewController; first launch will crash; subsequent launches have no effect.