title: Apple Pencil pen color is darker than the color given to PKInkingTool
body: <p>I've got the bare minimum apple pencil setup: a <code>PKCanvasView</code> named 'drawingView' given an inking tool as follows (to set the starting pen color):</p>
  <pre><code>let penColor = UIColor.white.withAlphaComponent(0.5)
  drawingView.tool = PKInkingTool(.pen, color: penColor, width: 15)
  </code></pre>
  <p>However, when I use the pen, it is extremely dark (I've tried this with several colors besides <code>.white</code>). Is this a glitch interal to PencilKit that others are experiencing, or am I missing something?</p>
  <p>thanks </p>