title: DispatchSourceTimer and Swift 3.0
body: <p>I can't figure out how to make dispatch timer work repeatedly in Swift 3.0. My code:</p>
  
  <pre><code>let queue = DispatchQueue(label: "com.firm.app.timer",
                            attributes: DispatchQueue.Attributes.concurrent)
  let timer = DispatchSource.makeTimerSource(flags: DispatchSource.TimerFlags(rawValue: UInt(0)),
                                             queue: queue)
  
  timer.scheduleRepeating(deadline: DispatchTime.now(),
                          interval: .seconds(5),
                          leeway: .seconds(1)
  )
  
  timer.setEventHandler(handler: {
       //a bunch of code here
  })
  
  timer.resume()
  </code></pre>
  
  <p>Timer just fires one time and doesn't repeat itself like it should be. How can I fix this?</p>