How can I use Autolayout to set constraints on my UIScrollview?

Question

I have spent two days trying out the various solutions for Mixed and Pure Autolayout approaches to achieve what was a trivial scrollview setup prior to autolayout, and it\'s

Answer 1

Similar problem I'm having today with iOS 8.4, Xcode 6.4

There a view containing a scroll view, containing a contentView (UIView) containing subviews.

Everything is auto layout everywhere. The scrollview edges are pinned to the parent views edges with constraints. The content view edges are pinned to the scroll view edges with constraints.

Originally the content view would refuse to size as the full width of the scroll view. I had to add an additional constraint on the content view to have its width match the parent scroll view. Or I could set a contentView.centerX == scrollView.centerX constraint. Either one of those in addition to pinning the edges suddenly made the content view properly size.

// Either one of these additional constraints are required to get autolayout to correctly layout the contentView. Otherwise contentView size is its minimum required size
scrollView.addConstraint(NSLayoutConstraint(item: contentView, attribute: .CenterX, relatedBy: .Equal, toItem: scrollView, attribute: .CenterX, multiplier: 1.0, constant: 0))
scrollView.addConstraint(NSLayoutConstraint(item: contentView, attribute: NSLayoutAttribute.Width, relatedBy: .Equal, toItem: scrollView, attribute: .Width, multiplier: 1.0, constant: 0.0))

Pinning the edges of the content view to the scroll view using visual constraints of the form,

let cvConstraints = ["H:|[contentView]|", "V:|[contentView]|"]

I use a routine to iterate through the array and add them to the scrollView.