title: Change Tab Bar background transparency
body: <p>I am trying to make my Tab Bar in my tab bar controller to have a low opacity background, so it is semi transparent, i am trying to do this programatically, however the background changes to the correct color, but always appears solid, with no transparency.</p>
  
  <p>Here is the code in my TabBarViewController</p>
  
  <pre><code>class TabBarViewController: UITabBarController {
  
      override func viewDidLoad() {
          super.viewDidLoad()
  
          self.tabBar.unselectedItemTintColor = UIColor(red: 17.0/255.0, green: 70.0/255.0, blue: 95.0/255.0, alpha: 0.4)
          self.tabBar.barTintColor = UIColor(red: 17.0/255.0, green: 70.0/255.0, blue: 95.0/255.0, alpha: 0.5)
  
  
          // Do any additional setup after loading the view.
      }
  }
  </code></pre>