title: ios constraing a set of buttons to navigation item inside a uiview
body: <p>I create two buttons inside a UIView and by selecting each button I intend to display a subview. I created the views in auto layout. But I cannot set constraints from the UIView containing the buttons to the navigation item. So when I run it in simulator I don't see neither buttons nor the UIview but the color of the navigation item changes to that of the button's UIView Tint (in this case blue) looks like my buttons and the UIview are hidden somewhere. </p>
  
  <p><a href="https://i.stack.imgur.com/a04x0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/a04x0.png" alt="enter image description here"></a></p>
  
  <p>Display looks like this:
  <a href="https://i.stack.imgur.com/sd2gx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sd2gx.png" alt="enter image description here"></a></p>