Code for CodeSlicing episode creating the add animations in MyFitnessPal

MyFitnessPalAddAnimation.swift

//
//  MyFitnessPalAddAnimation.swift
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
//  of the Software, and to permit persons to whom the Software is furnished to do so,
//  subject to the following conditions:

//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
//  INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
//  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
//  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
//  AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
//  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//  Copyright © 2020 Adam Fordyce. All rights reserved.
//

import SwiftUI
import PureSwiftUI

private let buttonBlue = Color(red: 42/255, green: 99/255, blue: 228/255)

private typealias TitleAndSymbol = (title: String, symbol: SFSymbolName)

private let buttonTitlesAndSymbols: [[TitleAndSymbol]] = [
    [("Favorite", .star), ("Tag", .tag), ("Share", .square_and_arrow_up)],
    [("Comment", .text_bubble), ("Delete", .trash)]
]

private let defaultAnimation = Animation.easeInOut(duration: 0.2)
private let hideAnimation = defaultAnimation
private let showAnimation = Animation.spring(response: 0.3, dampingFraction: 0.6)

struct MyFitnessPalAddAnimation: View {
    @State private var showingButtons = false
    @State private var homeLocation = CGPoint.zero
    var body: some View {
        ZStack {
            Color.black.opacity(0.8)
                .opacityIfNot(self.showingButtons, 0)
                .animation(defaultAnimation)
            VStack(spacing: 60) {
                Spacer()
                ForEach(0..<buttonTitlesAndSymbols.count) { rowIndex in
                    HStack(spacing: 60) {
                        ForEach(0..<buttonTitlesAndSymbols[rowIndex].count) { colIndex in
                            MyFitnessPalButton(titleAndSymbol: buttonTitlesAndSymbols[rowIndex][colIndex])
                                .opacityIfNot(self.showingButtons, 0)
                                .offsetToPositionIfNot(self.showingButtons, self.homeLocation)
                        }
                    }
                }
                Circle()
                    .fill(buttonBlue)
                    .overlay(SFSymbol(.plus).foregroundColor(.white)
                        .rotateIf(self.showingButtons, -45.degrees))
                    .frame(48)
                    .geometryReader { (geo: GeometryProxy) in
                        self.homeLocation = geo.globalCenter
                }
                .onTapGesture {
                    withAnimation(self.showingButtons ? hideAnimation : showAnimation) {
                        self.showingButtons.toggle()
                    }
                }
            }
            .padding()
        }
        .edgesIgnoringSafeArea(.all)
    }
}

struct MyFitnessPalButton: View {
    fileprivate let titleAndSymbol: TitleAndSymbol
    var body: some View {
        Circle()
            .fillColor(.white)
            .overlay(SFSymbol(titleAndSymbol.symbol))
            .overlay(CaptionText(titleAndSymbol.title.uppercased(), .white, .semibold).fixedSize().yOffset(40))
            .frame(50)
    }
}

struct MyFitnessPalAddAnimation_Previews: PreviewProvider {
    struct MyFitnessPalAddAnimation_Harness: View {

        var body: some View {
            MyFitnessPalAddAnimation().previewDevice(.iPhone_8)
        }
    }

    static var previews: some View {
        MyFitnessPalAddAnimation_Harness()
    }
}