Allow dynamic UIScrollView content view sizes to work with AutoLayout

DynamicScrollViewContainer.swift

//
//  DynamicScrollViewContainer.swift
//  magicmark
//
//  Created by Mark Larah on 25/05/2015.
//  Copyright (c) 2015 Mark. All rights reserved.
//


import UIKit

class DynamicScrollViewContainer: UIView {
    
    var childScroll: UIScrollView?
   
    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        setUpChildScroll()
    }

    var delegate: DynamicScrollViewDelegate?
    
    func setUpChildScroll() {
        
        childScroll = UIScrollView(frame: CGRect(x: 0, y: 0, width: 1, height: 1))
        self.addSubview(childScroll!)
        
        // Set up constraints to stretch view to superview's edges
        var scrollConstraint1 = NSLayoutConstraint(
            item: childScroll!,
            attribute: NSLayoutAttribute.CenterY,
            relatedBy: NSLayoutRelation.Equal,
            toItem: self,
            attribute: NSLayoutAttribute.CenterY,
            multiplier: 1.0,
            constant: 0
        )
        
        var scrollConstraint2 = NSLayoutConstraint(
            item: childScroll!,
            attribute: NSLayoutAttribute.Height,
            relatedBy: NSLayoutRelation.Equal,
            toItem: self,
            attribute: NSLayoutAttribute.Height,
            multiplier: 1.0,
            constant: 0
        )
        
        var scrollConstraint3 = NSLayoutConstraint(
            item: childScroll!,
            attribute: NSLayoutAttribute.Width,
            relatedBy: NSLayoutRelation.Equal,
            toItem: self,
            attribute: NSLayoutAttribute.Width,
            multiplier: 1.0,
            constant: 0
        )

        var scrollConstraint4 = NSLayoutConstraint(
            item: childScroll!,
            attribute: NSLayoutAttribute.CenterX,
            relatedBy: NSLayoutRelation.Equal,
            toItem: self,
            attribute: NSLayoutAttribute.CenterX,
            multiplier: 1.0,
            constant: 0
        )
        
        childScroll!.setTranslatesAutoresizingMaskIntoConstraints(false)
        superview!.addConstraint(scrollConstraint1)
        superview!.addConstraint(scrollConstraint2)
        superview!.addConstraint(scrollConstraint3)
        superview!.addConstraint(scrollConstraint4)
        
    }
    
    func scrollToTop() {
        childScroll!.setContentOffset(CGPointMake(0, -childScroll!.contentInset.top), animated: false)
    }
    
}

DynamicUIView.swift

//
//  DynamicUIView.swift
//  magicmark
//
//  Created by Mark Larah on 25/05/2015.
//  Copyright (c) 2015 Mark. All rights reserved.
//

import UIKit

// Implement this protocol in the ViewController as shown in ViewController.swift
protocol DynamicUIViewDelegate {
    func didLayout(view: DynamicUIView)
}

class DynamicUIView: UIView {

    var delegate: DynamicUIViewDelegate?

    override func layoutSubviews() {
        super.layoutSubviews()
        delegate?.didLayout(self)
    }
    
    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        setConstraints()
    }
    
    func setConstraints() {
        if superview == nil {
            return ;
        }
        
        self.setTranslatesAutoresizingMaskIntoConstraints(false)

        var viewConstraint1 = NSLayoutConstraint(
            item: self,
            attribute: NSLayoutAttribute.Top,
            relatedBy: NSLayoutRelation.Equal,
            toItem: superview!,
            attribute: NSLayoutAttribute.Top,
            multiplier: 1.0,
            constant: 0
        )

        var viewConstraint2 = NSLayoutConstraint(
            item: self,
            attribute: NSLayoutAttribute.Width,
            relatedBy: NSLayoutRelation.Equal,
            toItem: superview!,
            attribute: NSLayoutAttribute.Width,
            multiplier: 1.0,
            constant: 0
        )
        
        superview!.addConstraint(viewConstraint1)
        superview!.addConstraint(viewConstraint2)
        
    }

}

ViewController.swift

//
//  ViewController.swift
//  Chabad
//
//  Created by Mark Larah on 25/05/2015.
//  Copyright (c) 2015 Mark. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet var pagesContainer: DynamicScrollViewContainer!

    @IBOutlet var page1: DynamicUIView!
    @IBOutlet var page2: DynamicUIView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        page1.delegate = self
        page2.delegate = self
    }
    
    func setCorrectScrollViewSize (pageView: UIView) {
        let lowestSubViewHeight = pageView.getLowestSubView().getBottomY()
        
        // Plus 9 for padding text at the bottom. You can change this conditionally
        let heightOfView = lowestSubViewHeight + 9
        pagesContainer!.childScroll!.contentSize = CGSize(width: UIScreen.mainScreen().bounds.width, height: heightOfView)
        pagesContainer!.scrollToTop()
    }
    
}

// MARK - DynamicUIViewDelegate
extension ViewController: DynamicUIViewDelegate {
    func didLayout(view: DynamicUIView) {
        setCorrectScrollViewSize(view)
    }
}

// MARK - UIView
extension UIView {
    
    func getBottomY () -> CGFloat {
        return self.frame.origin.y + self.frame.height
    }
    
    func getLowestSubView () -> UIView {
        var minView: UIView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: 0))
        for subview in self.subviews {
            if (subview as! UIView).getBottomY() > minView.getBottomY() {
                minView = subview as! UIView
            }
        }
        return minView
    }
    
}