BABABLA

VerticalSpacing.swift

//: Playground - noun: a place where people can play

import XCPlayground
import UIKit

class VerticalEqualSpacingView :UIView {
    
    var spacing:CGFloat = 0 {
        didSet {
            guard oldValue != spacing else { return }
            self.equalSpacing.forEach({$0.constant = spacing})
        }
    }
    
    var equalSpacing = [NSLayoutConstraint]()
    
    override func addSubview(view: UIView) {
        super.addSubview(view)
        equalSpacing.forEach({self.removeConstraint($0)})
        equalSpacing = calculateEqualSpacingConstraint()
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        let totalHeight = subviews.map({$0.frame.height}).reduce(0, combine: +)
        self.spacing = (self.frame.height - totalHeight) / CGFloat(subviews.count + 1)

    }
    
    func calculateEqualSpacingConstraint() -> [NSLayoutConstraint] {
        var previous: (UIView, NSLayoutAttribute) = (self, .Top)
        var constraints = [NSLayoutConstraint]()
        subviews.forEach { (view) -> () in
            let constraint = NSLayoutConstraint(item: view, attribute: .Top, relatedBy: .Equal, toItem: previous.0, attribute: previous.1, multiplier: 1, constant: spacing)
            previous = (view, .Bottom)
            self.addConstraint(constraint)
            constraints.append(constraint)
        }
        return constraints
    }
}

let container = VerticalEqualSpacingView(frame: CGRect(x: 0, y: 0, width: 300, height: 500))
container.backgroundColor = .whiteColor()

let labelA = UILabel(frame: .zero)
labelA.translatesAutoresizingMaskIntoConstraints = false
labelA.text = "Hello,world"
labelA.sizeToFit()
labelA.backgroundColor = UIColor.redColor()
labelA.heightAnchor.constraintEqualToConstant(100).active = true
container.addSubview(labelA)

let labelB = UILabel(frame: .zero)
labelB.translatesAutoresizingMaskIntoConstraints = false
labelB.text = "Sup"
labelB.sizeToFit()
labelB.backgroundColor = UIColor.redColor()
container.addSubview(labelB)

XCPlaygroundPage.currentPage.liveView = container