debuglayout.swift

import SwiftUI

extension View {
    func debugLog(_ name: String) -> some View {
        MyLayout(name: name) { self }
    }
}

struct MyLayout: Layout {
    var name: String
    func sizeThatFits(proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) -> CGSize {
        assert(subviews.count == 1)
        let result = subviews[0].sizeThatFits(proposal)
        print(name, proposal, result)
        return result
    }

    func placeSubviews(in bounds: CGRect, proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) {
        subviews[0].place(at: bounds.origin, proposal: proposal)
    }
}