ボタンを円形に展開する。Swift Playground用。

ビューの展開(円).swift

import SwiftUI
import PlaygroundSupport

/// ボタン
struct RoundButton: View {
    /// サイズ
    static let size: CGSize = .init(width: 32, height: 32)

    /// 画像
    let image: Image

    /// アクション
    let action: () -> Void

    var body: some View {
        ZStack {
            Circle()
                .fill(Color.white)
                .shadow(color: .black.opacity(0.2), radius: 1, x: 2, y: 2)
            Button(action: action, label: { image })
                .background(.white)
        }
        .frame(width: RoundButton.size.width, height: RoundButton.size.height)
    }
}

/// プレビュー
struct ContentView: View {
    /// 画面サイズ
    private let size: CGSize = .init(width: 500, height: 500)

    /// 半径
    private let r: CGFloat = 80

    /// ボタンデータ
    private let buttons: [(image: String, label: LocalizedStringResource)] = [
        ("a.circle.fill", "a"), ("b.circle.fill", "b"), ("c.circle.fill", "c"), ("d.circle.fill", "d")
    ]

    /// デフォルトのボタン位置
    private var defaultButtonPosition: CGPoint {
        .init(x: size.width - RoundButton.size.width / 2 - 16, y: size.height - RoundButton.size.height / 2 - 16)
    }

    /// 拡張フラグ
    @State private var isExpanded: Bool = false

    var body: some View {
        ZStack {
            ForEach(0..<buttons.count, id: \.self) { i in
                RoundButton(image: .init(systemName: buttons[i].image)) {
                    print(buttons[i].label)
                    withAnimation {
                        isExpanded.toggle()
                    }
                }
                .frame(width: RoundButton.size.width, height: RoundButton.size.height)
                .position(defaultButtonPosition)
                .offset(isExpanded ? expandPosition(position: i) : .zero)
                .opacity(isExpanded ? 1 : 0)
            }
            RoundButton(image: .init(systemName: isExpanded ? "chevron.up.circle" : "chevron.down.circle")) {
                withAnimation {
                    isExpanded.toggle()
                }
            }
            .frame(width: RoundButton.size.width, height: RoundButton.size.height)
            .position(defaultButtonPosition)
        }
        .frame(width: size.width, height: size.height)
    }

    /// 拡張時の位置
    /// - Parameter position: ボタン位置
    /// - Returns: 拡張時の位置
    private func expandPosition(position: Int) -> CGSize {
        let theta = (2.0 * .pi) / 4.0 / CGFloat(buttons.count - 1) * CGFloat(position)
        return .init(width: -r * cos(theta), height: -r * sin(theta))
    }
}

PlaygroundPage.current.setLiveView(ContentView())