Pasted

//
 
import UIKit
 
class AutoSizingStringDrawer: UIView {
    @NSCopying var attributedText = NSAttributedString() {
        didSet {
            self.setNeedsDisplay()
            self.invalidateIntrinsicContentSize()
        }
    }
    
    override func draw(_ rect: CGRect) {
        self.attributedText.draw(with: rect, options: [.truncatesLastVisibleLine, .usesLineFragmentOrigin], context: nil)
    }
    
    override var intrinsicContentSize: CGSize {
        let measuredSize = self.attributedText.boundingRect(
            with: CGSize(width:self.bounds.width, height:10000),
            options: [.truncatesLastVisibleLine, .usesLineFragmentOrigin],
            context: nil).size
        print("Drawer intrinsicContentSize:", measuredSize, "bounds:", bounds.size)
        return CGSize(width: UIView.noIntrinsicMetric, height: measuredSize.height.rounded(.up) + 5)
    }
    
    var currentWidth: CGFloat = 0.0
    override func layoutSubviews() {
        super.layoutSubviews()
        if currentWidth != bounds.width {
            currentWidth = bounds.width
            self.invalidateIntrinsicContentSize()
        }
        print("Drawer layoutSubviews bounds.size", bounds.size)
    }
    
}
 
class MyLabel: UILabel {
    
    override var intrinsicContentSize: CGSize {
        let sz = super.intrinsicContentSize
        print("MyLabel intrinsicContentSize:", sz, "bounds:", bounds.size)
        return sz
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        print("MyLabel layoutSubviews bounds.size:", bounds.size)
    }
 
}
 
class StringDrawer: UIView {
    @NSCopying var attributedText = NSAttributedString() {
        didSet {
            self.setNeedsDisplay()
            self.invalidateIntrinsicContentSize()
        }
    }
    
    override func draw(_ rect: CGRect) {
        self.attributedText.draw(with: rect, options: [.truncatesLastVisibleLine, .usesLineFragmentOrigin], context: nil)
    }
    
    override var intrinsicContentSize: CGSize {
        let measuredSize = self.attributedText.boundingRect(
            with: CGSize(width:self.bounds.width, height:10000),
            options: [.truncatesLastVisibleLine, .usesLineFragmentOrigin],
            context: nil).size
        print("Drawer intrinsicContentSize:", measuredSize, "bounds:", bounds.size)
        return CGSize(width: UIView.noIntrinsicMetric, height: measuredSize.height.rounded(.up) + 5)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        print("Drawer layoutSubviews bounds.size", bounds.size)
    }
    
}
 
class TestViewController: UIViewController {
    
    let testDrawer: StringDrawer = StringDrawer()
    let testLabel: MyLabel = MyLabel()
    
    let testString = "enough text to cause word wrapping to test the intrinsic content size issue."
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .yellow
        
        [testDrawer, testLabel].forEach { v in
            v.translatesAutoresizingMaskIntoConstraints = false
            view.addSubview(v)
        }
        
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            testDrawer.topAnchor.constraint(equalTo: g.topAnchor, constant: 100.0),
            testDrawer.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            testDrawer.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            
            testLabel.topAnchor.constraint(equalTo: g.topAnchor, constant: 200.0),
            testLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            testLabel.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
        ])
        
        testDrawer.backgroundColor = .cyan
        
        testLabel.backgroundColor = .green
        testLabel.numberOfLines = 0
        
        let drawerString = NSAttributedString(string: "Drawer: " + testString, attributes: [
            .foregroundColor : UIColor.darkText,
            .font : UIFont(name: "Helvetica", size: 14)!
        ])
        
        let labelString = NSAttributedString(string: "Label: " + testString, attributes: [
            .foregroundColor : UIColor.darkText,
            .font : UIFont(name: "Helvetica", size: 14)!
        ])
        
        testDrawer.attributedText = drawerString
        testLabel.attributedText = labelString
        
    }
    
}
 
/*
Console output with iPhone 8 / 14.0 / Simulator
 
Drawer intrinsicContentSize: (513.59765625, 16.1) bounds: (0.0, 0.0)
MyLabel intrinsicContentSize: (65536.0, 16.5) bounds: (0.0, 0.0)
MyLabel intrinsicContentSize: (65536.0, 16.5) bounds: (0.0, 0.0)
MyLabel intrinsicContentSize: (335.0, 32.5) bounds: (0.0, 0.0)
MyLabel intrinsicContentSize: (65536.0, 16.5) bounds: (0.0, 0.0)
MyLabel intrinsicContentSize: (335.0, 32.5) bounds: (0.0, 0.0)
MyLabel layoutSubviews bounds.size: (335.0, 32.5)
MyLabel layoutSubviews bounds.size: (335.0, 32.5)
Drawer layoutSubviews bounds.size (335.0, 22.0)
 
*/