title: How to make an async method to handle data from delegate?
body: <p>I use btstack to communicate between my iPhone and an external device. I want to send a special command to retrieve the device's special data. But I could only obtain the data from btstack's handlePacket: method . I could only handle the data using delegate.
  But I want to make a method like this:</p>
  
  <pre><code>- (void)readDataAsyncWithCompletionHandler:(Handler)handler
  </code></pre>
  
  <p>The handler block should obtain the data. 
  I don't know how to do .
  I made a Command class to do the command construction and sending.</p>
  
  <p>I know we can use await in c#! So how to deal with it in ios?</p>