title: AutoLayout: layout consistency with proportional element spacing with 3.5" and 4" screens
body: <p>I want to use AutoLayout to position controls with proportional vertical spacing between them (avoid cropping on a 3.5" screen, avoid blank bottom space on a 4" screen).</p>
  
  <p>As suggested in other answers, I can use spacer views with "Equal Height" constraints, changing multiplier where necessary. However, the final layout is not pixel-perfect, so the engine can't position them consistently.</p>
  
  <p>The symptoms:</p>
  
  <ol>
  <li><p>When I do an "Update All Frames" in IB, it doesn't fix misplaced views, but merely replaces them with other set of misplaced views.</p></li>
  <li><p>More importantly, at run time, I can see the controls momentarily jump a few pixels up or down, whenever I enter the view.</p></li>
  </ol>
  
  <p>How to I achieve the same consistent layout every time?</p>