WidthTest.swift

import UIKit
import AsyncDisplayKit

var calculatedWidth: CGFloat = 0

class ViewController: UIViewController {
    
    // MARK: Properties
    
    private let containerNode: WidthTestContainerNode
    
    // MARK: Lifecycle
    
    required init() {
        self.containerNode = WidthTestContainerNode()
        super.init(nibName: nil, bundle: nil)
    }
    
    required init(coder aDecoder: NSCoder) {
        fatalError("storyboards are incompatible with truth and beauty")
    }
    
    // MARK: UIViewController
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.view.backgroundColor = UIColor(red: 20.0/255.0, green: 20.0/255.0, blue: 20.0/255.0, alpha: 1.0)
        self.view.addSubview(self.containerNode.view)
    }
    
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        
        self.containerNode.measure(CGSizeMake(180, 142))
        self.containerNode.frame = CGRectMake(
            (self.view.bounds.size.width - self.containerNode.calculatedSize.width) / 2,
            (self.view.bounds.size.height - self.containerNode.calculatedSize.height) / 2,
            self.containerNode.calculatedSize.width,
            self.containerNode.calculatedSize.height)
    }
    
    override func preferredStatusBarStyle() -> UIStatusBarStyle {
        return UIStatusBarStyle.LightContent
    }
    
    override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
        return UIInterfaceOrientationMask.Portrait
    }
}

class WidthTestContainerNode: ASDisplayNode {
    
    // MARK: Properties
    
    let textNode: WidthTestTextNode
    
    private let blockNode: ASDisplayNode
    
    // MARK: Lifecycle
    
    required override init() {
        self.textNode = WidthTestTextNode()
        self.blockNode = ASDisplayNode()
        
        super.init()
        
        // Blue box
        self.backgroundColor = UIColor(red: 111.0/255.0, green: 168.0/255.0, blue: 222.0/255.0, alpha: 1.0)
        
        // Yellow box
        self.textNode.backgroundColor = UIColor(red: 255.0/255.0, green: 217.0/255.0, blue: 102.0/255.0, alpha: 1.0)
        self.textNode.attributedString = NSAttributedString(
            string: "asfhjashfasjkfhkas fkjasafhasfjhaskjfjkasf asfhjkashfjkas fashkjfh kajsf asfjasjhk fhkjasfhjk afsjkafsfhsj kasfhjkas sdfl jsdflk sdf",
            attributes: [NSForegroundColorAttributeName: UIColor.blackColor()])
        self.textNode.flexShrink = true
        self.textNode.flexGrow = true
        self.addSubnode(self.textNode)
        
        // Red box
        self.blockNode.backgroundColor = UIColor(red: 234.0/255.0, green: 153.0/255.0, blue: 153.0/255.0, alpha: 1.0)
        self.addSubnode(self.blockNode)
    }
    
    override func layout() {
        super.layout()
        
        // Display a red box where the extra space is
        let w = (self.textNode.calculatedSize.width - calculatedWidth)
        self.blockNode.frame = CGRectMake(
            CGRectGetMaxX(self.textNode.frame) - w,
            CGRectGetMinY(self.textNode.frame),
            w,
            self.textNode.frame.size.height)
    }
    
    // MARK: ASDisplayNode
    
    override func layoutSpecThatFits(constrainedSize: ASSizeRange) -> ASLayoutSpec {
        let hStack = ASStackLayoutSpec(
            direction: .Horizontal,
            spacing: 0,
            justifyContent: .Start,
            alignItems: .Start,
            children: [self.textNode])
        
        let vStack = ASStackLayoutSpec(
            direction: .Vertical,
            spacing: 0,
            justifyContent: .Start,
            alignItems: .Start,
            children: [hStack])
        
        return ASInsetLayoutSpec(
            insets: UIEdgeInsetsMake(8, 8, 8, 8),
            child: vStack)
    }
    
    class WidthTestTextNode: ASTextNode {
        
        // MARK: ASDisplayNode
        
        override func calculateSizeThatFits(constrainedSize: CGSize) -> CGSize {
            let size = super.calculateSizeThatFits(constrainedSize)
            
            // Store width to calculate size of red box
            calculatedWidth = size.width
            
            NSLog("Max Width: " + String(constrainedSize.width) + " | Calculated Width " + String(size.width))
            
            return CGSize(width: size.width, height: size.height)
        }
    }
}