title: How can I modify touch and drag sensitivity?
body: <p>I'm working on an app for a physically challenged population, and in testing we're finding that they have a lot of trouble with the default touch-drag functionality.</p>
  
  <p>We've got a screen where there's a grid of icons in a UIScrollView.  You can touch an icon to activate it, and you can touch-drag anywhere in the grid, including on an icon, to scroll the grid and see more icons.</p>
  
  <p>In iOS, the default behavior is that you touch and drag in one motion.  This requires a certain amount of physical coordination, and if you touch and pause and <em>then</em> drag, or drag a little off course, the system treats this as a simple touch.  So our testers are doing things like:</p>
  
  <ul>
  <li><p>Touch, pause for a moment, and then try to drag.  The grid doesn't scroll.  If they were trying to scroll by dragging an icon, when they release the touch, it activates the icon instead.</p></li>
  <li><p>Touch, try to drag vertically (the only supported direction), but instead veer a little bit horizontally first.  Same outcome as above.</p></li>
  </ul>
  
  <p>So the question is: is there a way to override the touch processing to build in more tolerance for slowness or drag inaccuracy, so that the app will correctly interpret the above actions as scroll requests?</p>