title: Swift Transparent NavigationBar not working sometimes
body: <p>I have created a project with Main activity, Second Activity and UITabBarController</p>
  <p>I open Second activity from MainActivity and transparent navigationbar work great.</p>
  <p>then i go back to Mainactivity and I open UITabBarController</p>
  <p>and I'm back to the Mainactivity again. The problem starts here.</p>
  <p>I open Second activity again but transparent navigationbar not work. It looks white.</p>
  <p>I spent hours on this problem but i couldn't solve it. I need your help.</p>
  <p>Sorry for my bad English.</p>