title: Temporary attributes on NSMutableAttributedString that are removed when string is edited
body: <p>I was wondering if there is a way to set attributes on an NSMutableAttributedString that will go away when the string is edited. For example, you know how if you type in some wrong text on your iOS device, it gets underlined with a red dotted line(Example: "dogg"). In this example, if you then would remove the last "g" so the word would now be "dog" the red dotted underline goes away since it's a valid English word. How can I replicate this behavior with a custom UITextField? Currently I am using a NSMutableAttributedString to underline a portion of a custom string of mine but the problem is that the user can then go back, and add text to say the middle of the underlined part and the new text they type gets the underline also. I want a portion of my string to get an underline, like the red underline in the above example, but I want the underline to go away when the underlined portion of the string is edited. </p>
  
  <p>How can I do this?</p>
  
  <p>Also, this is for a jailbreak tweak so I am totally open to using private api's. </p>
  
  <p>Thanks!</p>