title: iOS Why is requestEndDate earlier than requestStartDate?
body: <p>show code</p>
  <pre><code>    func urlSession(_ session: URLSession,
                      task: URLSessionTask,
                      didFinishCollecting metrics: URLSessionTaskMetrics) {
          
          guard metrics.transactionMetrics.count &gt; 0 else { return }
          for metric in metrics.transactionMetrics where metric.resourceFetchType == .networkLoad {
              
              if let requestStartDate = metric.requestStartDate, let requestEndDate = metric.requestEndDate {
                  let requestDuration: Double = ceil(requestEndDate.timeIntervalSince(requestStartDate)*1000)
                  print(&quot;requestStartDate:\(requestStartDate.timeIntervalSince1970)&quot;)
                  print(&quot;requestEndDate:\(requestEndDate.timeIntervalSince1970)&quot;)
              }
              
          }
      }
  </code></pre>
  <p>output:</p>
  <blockquote>
  <p>requestStartDate:1576467073.038733</p>
  <p>requestEndDate:1576467071.590589</p>
  </blockquote>
  <p>My question is why is requestEndDate earlier than requestStartDate?</p>