Vertically stacking views

VerticallyStackViewHelpers.swift

/**
Adds views to containerView, along with constraints to stack them vertically
and fill horozintally.
*/
func addVerticallyStackedViews(views:[UIView], toView containerView:UIView) -> [NSLayoutConstraint]
{
  for v in views {
    v.setTranslatesAutoresizingMaskIntoConstraints(false)
    containerView.addSubview(v)
  }
  
  var cs:[NSLayoutConstraint] = []
  if let topView = views.first {
    cs.append(NSLayoutConstraint(item: containerView, attribute: .Top, relatedBy: .Equal, toItem: topView, attribute: .Top, multiplier: 1.0, constant: 0))
  }
  if let bottomView = views.last {
    cs.append(NSLayoutConstraint(item: containerView, attribute: .Bottom, relatedBy: .Equal, toItem: bottomView, attribute: .Bottom, multiplier: 1.0, constant: 0))
  }
  let offset = Array(views[1..<views.count])
  for (aboveView,belowView) in Zip2(views,offset) {
    cs.append(NSLayoutConstraint(item:aboveView,attribute:.Bottom, relatedBy:.Equal, toItem:belowView, attribute:.Top,multiplier:1.0,constant:0))
  }
  
  for v in views {
    let leftC = NSLayoutConstraint(item: v, attribute: .Left, relatedBy: .Equal, toItem: containerView, attribute: .Left, multiplier: 1, constant: 0)
    let rightC = NSLayoutConstraint(item: v, attribute: .Right, relatedBy: .Equal, toItem: containerView, attribute: .Right, multiplier: 1, constant: 0)
    cs.append(leftC)
    cs.append(rightC)
  }
  
  NSLayoutConstraint.activateConstraints(cs)
  return cs
}