Julio Carrettoni (@dev_jac) asked how to arrange 2 labels in an H-stack which have the same but minimal width. In UIKit, you would use autolayout constraints to tie the widths together but we do not have that in SwiftUI. We have to think different!

As each element is responsible for sizing itself, you need to calculate the desired column width before they are rendered and pass that down to the elements so that they can size themselves accordingly.

Making the columnWidth a state variable means that when the view appears you can calculate the column width and update the state with the new width. This causes a redraw with the correct width.

Here’s a quick example:

//
//  ContentView.swift
//  Columns
//
//  Created by Andrew Eades on 23/07/2019.
//  Copyright © 2019 Andrew Eades. All rights reserved.
//

import SwiftUI

struct ContentView: View {
    @State private var columns: [ColumnModel] = [
        ColumnModel(text: "Longer Column"),
        ColumnModel(text: "Shorty")
    ]
    
    @State private var columnWidth: Length = 100
    
    let font = Font.system(.body)
    // need a UI font because I haven't figured out
    // how to get the size of the font yet
    let uiFont = UIFont.boldSystemFont(ofSize: 20)

    var body: some View {
        HStack {
            ForEach(columns, id: \.self) { column in
                Text(column.text)
                    .font(self.font)
                    .frame(minWidth: self.columnWidth, maxWidth: self.columnWidth)
                    .border(Color.black)
            }
        }
        .onAppear(perform: self.calculateColumnWidth)
        .padding()
        .border(Color.blue)
    }
 
    
    private func calculateColumnWidth() {
        let minimumWidth = columns
        .map {
            $0.text.width(usingFont: self.uiFont)
        }
        .reduce(0) {
            max($0, $1)
        }
        
        self.columnWidth = minimumWidth
    
    }
}

struct ColumnModel: Hashable {
    let text: String
}

extension String {
    
    func width(usingFont font: UIFont) -> CGFloat {
        
        let size = self.size(withAttributes:[.font: font])
        
        return size.width
    }
}