title: UITableView cannot scroll
body: <p>I have a tab bar, and two of the tabBarController.viewControllers has tableview inside.</p>
  
  <p>When I launch the App. tab 1's tableview cannot scroll. When switch to tab 2 and switch back to tab 1. the tab 1's tableview can scroll.</p>
  
  <p>So strange! Can anyone give a hint?</p>
  
  <p>Is it related to number of rows? p.s. both of tableviews' frame is not filled with enough rows.</p>
  
  <p>Thanks.</p>