title: UIButtons at the bottom of UIScrollView not working
body: <p>I created a UIScrollView in my storyboards and have added 12 UIButtons in a container View which is inside the UIScrollView.</p>
  
  <p>when running on the iPhone 5s simulator, 9 of the buttons can be seen on the screen, the rest of the buttons only can be seen when you scroll down.</p>
  
  <p>the 9 buttons that can be initially seen on the screen can be interacted with. However the 3 buttons at the bottom of the scroll view (which have to be scrolled to in order to be seen) cannot be interacted with.</p>
  
  <p>I ran the app on an iPhone 6 simulator which displays all 12 of the buttons on the screen without having to scroll and the bottom 3 buttons work.</p>
  
  <p>I am using autolayout.</p>
  
  <p>I have tried fiddling with the contentSize of the UIScrollView and it does not help. </p>