Setting equal widths in swiftUI.

WidthEqualiser.swift

import SwiftUI

struct ContentView: View {
    @State var width: CGFloat? = nil

    var body: some View {
        Form{
            ForEach(0..<115){ i in
                Row(place: i, width: $width)
            }
        }.modifier(ColumnWidth(width:$width))
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}


struct Row: View{
    let place: Int
    @Binding var width: CGFloat?

    func formatted()->String{
        let value = NSNumber(value: place + 1)
        let formatter = NumberFormatter()
        formatter.numberStyle = .ordinal
        return formatter.string(from: value)!
    }
    
    var body: some View{
        HStack{
            Text(formatted())
                .frame(width: width, alignment: .leading)
                .background(ColumnWidthEqualiserView())
            Color.red
                .frame(width: 30, height: 30)
                .clipShape(Circle())
            Text("Name")
            
            Spacer()
            Text("Details go here")
                .foregroundColor(.gray)
        }
    }
}

struct ColumnWidthPreference: Equatable {
    let width: CGFloat
}

struct ColumnWidthPreferenceKey: PreferenceKey {
    typealias Value = [ColumnWidthPreference]

    static var defaultValue: [ColumnWidthPreference] = []

    static func reduce(value: inout [ColumnWidthPreference], nextValue: () -> [ColumnWidthPreference]) {
        value.append(contentsOf: nextValue())
    }
}

struct ColumnWidthEqualiserView: View {
    var body: some View {
        GeometryReader { geometry in
            Rectangle()
                .fill(Color.clear)
                .preference(
                    key: ColumnWidthPreferenceKey.self,
                    value: [ColumnWidthPreference(width: geometry.frame(in: CoordinateSpace.global).width)]
                )
        }
    }
}

struct ColumnWidth: ViewModifier {
    @Binding var width: CGFloat?
    func body(content: Content) -> some View {
    content
        .onPreferenceChange(ColumnWidthPreferenceKey.self) { preferences in
            for p in preferences {
                let oldWidth = self.width ?? CGFloat.zero
                if p.width > oldWidth {
                    self.width = p.width
                }
            }
        }
    }
}