MrSelig.swift

struct ContentView: View {
    @State var pictureExpanded = false
    
    var body: some View {
        VStack(alignment: .leading, spacing: 0) {
            Text("Once upon a time there was a turtle named George who made friends with a giraffe at the local water park and then they went on lots of adventures together.")
            
            Button {
                withAnimation {
                    pictureExpanded.toggle()
                }
            } label: {
                Text("Tap to \(pictureExpanded ? "hide" : "see") a pretty picture")
            }
            
            /// Wrap transitioning view.
            /// - Note: `ZStack` works, `Group` does not.
            ZStack {
                if pictureExpanded {
                    Image("Snow")
                        /// Scale to fit.
                        .resizable()
                        .scaledToFit()
                        /// Transition causes `ZStack` bounds to resize.
                        .transition(.scale)
                        /// For layout only, do not display.
                        .opacity(0)
                }
            }
                /// Use parent's full width.
                .frame(maxWidth: .infinity)
                /// Background prevents this from modifying stack layout,
                /// which `maxHeight: .infinity` does.
                .background {
                    /// Credit robb.
                    Image("Snow")
                        .resizable()
                        .scaledToFit()
                        .fixedSize(horizontal: false, vertical: true)
                        .frame(minHeight: .zero, maxHeight: pictureExpanded ? .infinity : .zero)
                        .clipped()
                        .contentShape(Rectangle())
                }
                        
            Text("The giraffe's name was Leonard, and together George and Leonard became the best of friends and did all sorts of cool things together like climbing a mountain.")
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}