Resize superview with autolayout depending on largest subview - swift

Question

What is the best practice to resize superview with autolayout if we have inner NSView columns with dynamic heights?
For example. If we have two column layout, where left column height is bigger than right column, the superview height should be as right column height. Than, if we change right column height to be bigger than left column height, superview height should change to height of right column. How to accomplish this?
I made sample project to test this:
Initially we have layout with two columns, where .Bottom constraint of left NSView is attached to bottom of superview.
If we press Make Right Bigger button, I make height of right NSView bigger than left one.
So I want here superview to change height depending on bigger column (right column). Is there a good practice to do so?
Code:
import Cocoa
class ViewController: NSViewController {
let leftView = NSView()
let rightView = NSView()
let button = NSButton()
var rightViewHeightConstraint: NSLayoutConstraint?
override func loadView() {
self.view = TestView()
}
override func viewDidLoad() {
super.viewDidLoad()
leftView.backgroundColor = NSColor.redColor()
rightView.backgroundColor = NSColor.orangeColor()
layoutLeft(view, insertView: leftView)
layoutRight(view, insertView: rightView)
button.title = "Make Right Bigger"
button.target = self
button.action = "makeBigger:"
ViewControllerLayout.layoutBotton(view, insertView: button, bottom: -20)
}
func makeBigger(sender: AnyObject) {
rightViewHeightConstraint?.animator().constant = 150.0
}
func layoutLeft(containerView: NSView, insertView: NSView) {
insertView.translatesAutoresizingMaskIntoConstraints = false
containerView.addSubview(insertView)
let c1 = NSLayoutConstraint(item: insertView, attribute: .Left, relatedBy: .Equal, toItem: containerView, attribute: .Left, multiplier: 1.0, constant: 0.0)
let c2 = NSLayoutConstraint(item: insertView, attribute: .Width, relatedBy: .Equal, toItem: containerView, attribute: .Width, multiplier: 0.5, constant: 0.0)
let c3 = NSLayoutConstraint(item: insertView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 100.0)
let c4 = NSLayoutConstraint(item: insertView, attribute: .Top, relatedBy: .Equal, toItem: containerView, attribute: .Top, multiplier: 1.0, constant: 0.0)
let c5 = NSLayoutConstraint(item: insertView, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1.0, constant: -60.0)
containerView.addConstraint(c1)
containerView.addConstraint(c2)
containerView.addConstraint(c3)
containerView.addConstraint(c4)
containerView.addConstraint(c5)
}
func layoutRight(containerView: NSView, insertView: NSView) {
insertView.translatesAutoresizingMaskIntoConstraints = false
containerView.addSubview(insertView)
let c1 = NSLayoutConstraint(item: insertView, attribute: .Right, relatedBy: .Equal, toItem: containerView, attribute: .Right, multiplier: 1.0, constant: 0.0)
let c2 = NSLayoutConstraint(item: insertView, attribute: .Width, relatedBy: .Equal, toItem: containerView, attribute: .Width, multiplier: 0.5, constant: 0.0)
let c3 = NSLayoutConstraint(item: insertView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: 50.0)
let c4 = NSLayoutConstraint(item: insertView, attribute: .Top, relatedBy: .Equal, toItem: containerView, attribute: .Top, multiplier: 1.0, constant: 0.0)
let c5 = NSLayoutConstraint(item: insertView, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1.0, constant: -60.0)
containerView.addConstraint(c1)
containerView.addConstraint(c2)
containerView.addConstraint(c3)
containerView.addConstraint(c4)
// containerView.addConstraint(c5) // Cant add .Bottom constraint here, because of different column sizes.
rightViewHeightConstraint = c3
}
}
struct ViewControllerLayout {
static func layoutBotton(containerView: NSView, insertView: NSView, bottom: Double) {
insertView.translatesAutoresizingMaskIntoConstraints = false
containerView.addSubview(insertView)
containerView.addConstraint(NSLayoutConstraint(item: insertView, attribute: .CenterX, relatedBy: .Equal, toItem: containerView, attribute: .CenterX, multiplier: 1.0, constant: 0.0))
containerView.addConstraint(NSLayoutConstraint(item: insertView, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1.0, constant: CGFloat(bottom)))
}
}
Download test project: GitHub

Answer 1

Managed to accomplish this with constraints only. Just added the container view for columns and set its height as GreaterThanOrEqual to left column and right column.
view.addConstraint(NSLayoutConstraint(item: containerView, attribute: .Height, relatedBy: .GreaterThanOrEqual, toItem: leftView, attribute: .Height, multiplier: 1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: containerView, attribute: .Height, relatedBy: .GreaterThanOrEqual, toItem: rightView, attribute: .Height, multiplier: 1, constant: 0))

Answer 2

First create a constraint on superview with height
let heightConstraint = NSLayoutConstraint(item: view, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: greaterHeightAmongTwoColumns)
As discussed in the comment, you can post a notification and then let the super view know the updated frame. Super view would check if the updated height of any of the two columns is greater than its current height and update its heightConstraint declared above and then call
[self layoutIfNeeded]
on the superview's superview so that it is laid out with the new frame.