title: APNS? Or Polling? Which is more reliable?
body: <p>I'm working on a small messaging app, similar to IM or SMS text messages.  I'm obviously planning on using Apple's Push Notification Service (APNS) for notifying users of new messages when the app is not running.  The question is, what about when it <em>is</em> running?  Should I rely on APNS to notify the app when to refresh the list of messages that the user has received?  Or, should I do periodic polling to grab any new messages?</p>
  
  <p>My app will be making use of RestKit 0.20 as its web service client library.  Polling should be easy enough to configure there, but I'm concerned about the additional overhead of creating the connections, as well as the increased bandwidth utilization that polling will create.</p>
  
  <p>Is APNS reliable enough that I can use it to trigger a UI refresh when a new message is received?  Or should I handle it manually within the app itself via polling?</p>