because ... :(

MultilineLabel.swift

import Foundation

// based on: http://stackoverflow.com/questions/18118021/how-to-resize-superview-to-fit-all-subviews-with-autolayout
// required so we can have multiline labels properly resize their height based on content

class MultilineLabel: UILabel {
    override func layoutSubviews() {
        super.layoutSubviews()
        
        if numberOfLines == 0 && preferredMaxLayoutWidth != CGRectGetWidth(frame) {
            preferredMaxLayoutWidth = frame.size.width
            setNeedsUpdateConstraints()
        }
    }
    
    override func intrinsicContentSize() -> CGSize {
        var s = super.intrinsicContentSize()
        if numberOfLines == 0 {
            // found out that sometimes intrinsicContentSize is 1pt too short!
            s.height += 1
        }
        return s
    }
}