SwiftUIRemakeConstraintsApp.swift

import SwiftUI

@main
struct SwiftUIRemakeConstraintsApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .windowResizability(.contentSize)
    }
}

struct ContentView: View {
    @State var size: CGSize?
    
    var body: some View {
        ZStack(alignment: .top) {
            VStack(alignment: .leading, spacing: 20) {
                HStack(alignment: .top) {
                    Image(nsImage: .init(named: NSImage.cautionName)!)
                        .resizable()
                        .scaledToFit()
                        .frame(width: 64, height: 64)
                    
                    Text("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit")
                        .fixedSize(horizontal: false, vertical: true)
                        .readSize($size)
                        .frame(idealWidth: size?.width, minHeight: size?.height)
                }
                
                HStack {
                    Button { } label: {
                        ZStack {
                            Text("Lots of text here")
                                .fixedSize()
                            
                            Text("Cancel")
                                .hidden()
                            
                            Text("OK")
                                .hidden()
                        }
                    }
                    
                    Spacer(minLength: 12)
                    
                    Button { } label: {
                        ZStack {
                            Text("Lots of text here")
                                .hidden()
                            
                            Text("Cancel")
                                .fixedSize()
                            
                            Text("OK")
                                .hidden()
                        }
                    }
                    
                    Button { } label: {
                        ZStack {
                            Text("Lots of text here")
                                .hidden()
                            
                            Text("Cancel")
                                .hidden()
                            
                            Text("OK")
                                .fixedSize()
                        }
                    }
                }
            }
            .padding()
        }
    }
}

struct SizePreference: PreferenceKey {
    static let defaultValue: CGSize? = nil
    
    static func reduce(value: inout CGSize?, nextValue: () -> CGSize?) {
        value = nextValue()
    }
}

extension View {
    func readSize(_ size: Binding<CGSize?>) -> some View {
        background {
            GeometryReader { proxy in
                Color.clear
                    .preference(key: SizePreference.self, value: proxy.size)
                    .onPreferenceChange(SizePreference.self) { size.wrappedValue = $0 }
            }
        }
    }
}

#Preview {
    ContentView()
}