title: Is it possible to pause a CAEmitterLayer?
body: <p>I have a <code>CAEmitterLayer</code> instance that emits some <code>CAEmitterCells</code>. I'm wondering, is it possible to pause this layer such that no new <code>CAEmitterCells</code> are produced and the ones that have been produced remained fixed in their position on the screen? Then, when the <code>CAEmitterLayer</code> instance is "un-paused", the fixed <code>CAEmitterCells</code> on the screen start to move again.</p>
  
  <p>Thanks for any help here.</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Setting:</p>
  
  <pre><code>emitterLayer.speed = 0.1
  </code></pre>
  
  <p>where <code>emitterLayer</code> is an instance of a subclass of <code>CAEmitterLayer</code>, just <strong>removes the layer completely from the view</strong>.</p>
  
  <p>Setting:</p>
  
  <pre><code>emitterLayer.lifetime = 0.0
  </code></pre>
  
  <p>just <strong>stops any new <code>emitterCells</code> being produced but doesn't "freeze" the existing <code>emitterCells</code> at the current position</strong>.</p>