title: Is there a UITextField keyboard type that like a number pad but allows negative numbers?
body: <p>I am setting the UIKeyboardType as UIKeyboardTypeNumberPad on my UITextFields. However, this only allows the user to enter positive integers. I need the user to be able to enter negative or positive integers. Is there a UIKeyboardType that is identical to  UIKeyboardTypeNumberPad but also includes the "-" (minus) symbol, and if not is there a way I can create this?</p>
  
  <p>Thanks.</p>