title: iOS: How to access the `UIKeyboard`?
body: <p>I want to get a pointer reference to <code>UIKeyboard *keyboard</code> to the keyboard on screen so that I can add a transparent subview to it, covering it completely, to achieve the effect of <a href="https://stackoverflow.com/questions/5915559/how-to-disable-a-uitextfield-keyboard-without-hiding-it/6457114#6457114">disabling the <code>UIKeyboard</code> without hiding it</a>.</p>
  
  <p>In doing this, can I assume that there's only one <code>UIKeyboard</code> on the screen at a time? I.e., is it a singleton? Where's the method <code>[UIKeyboard sharedInstance]</code>. Brownie points if you implement that method via a category. Or, even more brownie points if you convince me why it's a bad idea to assume only one keyboard and give me a better solution.</p>