ClearLongPressGestureView.swift

import SwiftUI
import UIKit

/// UIKit でジェスチャを取得するための透明な View
///
/// overlay で利用する
/// 参考 https://stackoverflow.com/a/57943387/1567777
struct ClearLongPressGestureView: UIViewRepresentable {
    let onChanged: (Bool) -> Void

    final class Coordinator: NSObject, UIGestureRecognizerDelegate {
        let onChanged: (Bool) -> Void

        init(onChanged: @escaping (Bool) -> Void) {
            self.onChanged = onChanged
        }

        public func gestureRecognizer(_: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith _: UIGestureRecognizer) -> Bool {
            true
        }

        @objc func didLongPress(_ gesture: UILongPressGestureRecognizer) {
            print("didLongPress\(gesture.state.rawValue)")
            switch gesture.state {
            case .possible:
                break
            case .began:
                onChanged(true)
            case .ended, .cancelled, .failed:
                onChanged(false)
            default:
                break
            }
        }
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(onChanged: onChanged)
    }

    func makeUIView(context: UIViewRepresentableContext<ClearLongPressGestureView>) -> UIView {
        let view = UIView()
        view.backgroundColor = .clear

        let longPress = UILongPressGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.didLongPress))
        longPress.minimumPressDuration = 0
        longPress.delaysTouchesBegan = false
        longPress.delegate = context.coordinator
        view.addGestureRecognizer(longPress)

        return view
    }

    func updateUIView(_: UIView, context _: UIViewRepresentableContext<ClearLongPressGestureView>) {}
}

ExactTapButtonStyle.swift

import SwiftUI

/// 厳密に frame を当たり判定とした ButtonStyle
///
/// タップ時に少し透明にする
struct ExactTapButtonStyle: PrimitiveButtonStyle {
    enum Position {
        case overlay
        case background
    }

    /// タップ判定の位置
    /// ボタンを入れ子にするときには親に .background, 子に .overlay を指定すること
    let position: Position
    @State private var isPressing: Bool = false

    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .opacity(isPressing ? 0.7 : 1)
            .background {
                if position == .background {
                    TransparentTapArea(isPressing: $isPressing) { _ in
                        configuration.trigger()
                    }
                }
            }
            .overlay {
                if position == .overlay {
                    TransparentTapArea(isPressing: $isPressing) { _ in
                        configuration.trigger()
                    }
                }
            }
    }
}

/// タップ判定を行うための透明な View
private struct TransparentTapArea: View {
    @Binding var isPressing: Bool
    let action: (CGPoint) -> Void

    var body: some View {
        GeometryReader { proxy in
            Color.clear
                .contentShape(Rectangle())
                .overlay {
                    // onLongPressGesture を使うと ScrollView のスクロールを阻害するため
                    // UIKit でタップ判定を行う
                    ClearLongPressGestureView { value in
                        isPressing = value
                    }
                }
                .onTapGesture { location in
                    if proxy.size.contains(location) {
                        action(location)
                    }
                }
        }
    }
}

private extension CGSize {
    func contains(_ point: CGPoint) -> Bool {
        point.x >= 0
            && point.y >= 0
            && point.x < width
            && point.y < height
    }
}