title: Update Frames & Constraints in Xcode (Interface Builder)
body: <p>I have been learning Xcode and iOS and things are going well with coding but I am confused about a few options in interface builder.</p>
  
  <p>It seems that when I add a contraint I can choose to "Update Frames" and then either "Items of new contraints" or "All Frames" but it seems that I don't always need to do this... sometimes I do and sometimes I don't - I don't think I truly understand the concept. It seems to be optional. When is the case to choose it or not?</p>
  
  <p>Once a constraint is added, then should that be it?</p>
  
  <p>There is also a context menu (Resolve autolayout issues) (3rd item on the bottom on interface builder, represented by a triangle between 2 vertical lines) which also allows me to Force Update of constraint or update of frame. Why is this needed ? I notice the options inside are usually disabled so I presume this becomes active when there are issues ?</p>
  
  <p>I have tried searching the internet and I can't find anything specific; the more I read, the more confused I seem to get.</p>
  
  <p>Also, a sanity check: a frame is the bounding box of every single control (view) not just the viewcontrol, so every view (control) as its own frame. Is this correct?</p>