この記事は何？

Section1「Add Hiking Data to the App」で作成するビューのコードを読んでみました。

環境

macOS 11.2.1
Xcode 12.4
Swift 5.3

HikeView

HikeViewの定義

struct HikeView: View {
    var hike: Hike
    @State private var showDetail = false

    var body: some View {
        VStack {
            HStack {
                HikeGraph(hike: hike, path: \.elevation)
                    .frame(width: 50, height: 30)
                    .animation(nil)

                VStack(alignment: .leading) {
                    Text(hike.name)
                        .font(.headline)
                    Text(hike.distanceText)
                }

                Spacer()

                Button(action: {
                    self.showDetail.toggle()
                }) {
                    Image(systemName: "chevron.right.circle")
                        .imageScale(.large)
                        .rotationEffect(.degrees(showDetail ? 90 : 0))
                        .padding()
                }
            }

            if showDetail {
                HikeDetail(hike: hike)
            }
        }
    }
}

HikeViewの外観

HikeViewを構成するビュー階層

状態変数showDetailの挙動

Button(action: {
    self.showDetail.toggle()                
}) {
    ...
}

if showDetail {
    HikeDetail(hike: hike)            
}