title: Debugging URLSession (in iOS 10)
body: <p>I am having trouble with a <code>URLSession</code> that creates and resumes a <code>URLSessionDataTask</code> in the sense that I expect subsequent calls to certain methods in the session's (and task`s) delegate but apparently no such calls occur. </p>
  
  <p>How can I debug <code>URLSession</code> in a situation like this? For instance, can I request log output from it e.g. to find out when it sends or receives HTTP traffic or when it attempts to call a method in the delegate but cannot find the relevant implementation (e.g. because the method signature in the implementation may be slightly off).</p>