title: When does a touchesBegan become a touchesMoved?
body: <p>When you drag a finger across the iPhone touchscreen, it generates <code>touchesMoved</code> events at a nice, regular 60Hz.</p>
  
  <p>However, the transition from the initial <code>touchesBegan</code> event to the first <code>touchesMoved</code> is less obvious: sometimes the device waits a while. </p>
  
  <p>What's it waiting for? Larger time/distance deltas? More touches to lump into the event?</p>
  
  <p>Does anybody know?</p>
  
  <p><strong>Importantly</strong>, this delay does not happen with subsequent fingers, which puts the first touch at a distinct disadvantage. It's very asymmetric and bad news for apps that demand precise input, like games and musical instruments.</p>
  
  <p>To see this bug/phenomenon in action</p>
  
  <ol>
  <li><p><em>slowly</em> drag the iPhone screen unlock slider to the right. note the sudden jump &amp; note how it doesn't occur if you have another finger resting anywhere else on the screen</p></li>
  <li><p>try "creeping" across a narrow bridge in any number of 3D games. Frustrating!</p></li>
  <li><p>try a dual virtual joystick game &amp; note that the effect is mitigated because you're obliged to never end either of the touches which amortizes the unpleasantness.</p></li>
  </ol>
  
  <p>Should've logged this as a bug 8 months ago.</p>