title: get NSRunLoop instance
body: <p>I have a class which inherits NSThread:</p>
  
  <pre><code>@interface MyService : NSThread {
  ...
  }
  </code></pre>
  
  <p>In another class, I get a instance of <code>MySerivce</code>:</p>
  
  <pre><code>MyService *service = [self getServiceInstance];
  
  // here, how can I get the NSRunLoop instance out from service ?
  </code></pre>
  
  <p>I want to get the <code>NSRunLoop</code> instance of <code>service</code> , how to get it?</p>