2022-03-19 第二课完整代码

import SwiftUI

struct ContentView: View {
    var emojis = ["❤️", "🧡", "💙", "🖤","💚","💛","💜","🤎","💔","💗","💘","💝","💖","💓","💕"]
    @State var emojiCount = 6
    
    var body: some View {
        VStack {
            ScrollView {
                LazyVGrid(columns: [GridItem(.adaptive(minimum: 65))]) {
                    ForEach(emojis[0..<emojiCount], id: \.self) { emoji in
                        CardView(content: emoji)}
                    .aspectRatio(2/3, contentMode: .fit)
                }
            }
            .foregroundColor(.red)
            Spacer()
            HStack {
                add
                Spacer()
                remove
            }
            .font(.largeTitle)
        }
        .padding()
    }
    
    var remove: some View {
        Button {
            if emojiCount > 1 {
                emojiCount -= 1
            }
        } label: {
            Image(systemName: "minus.circle")
        }
    }
    var add: some View {
        Button {
            if emojiCount < emojis.count {
                emojiCount += 1
            }
        } label: {
            Image(systemName: "plus.circle")
        }
    }
}

struct CardView: View {
    var content: String
    @State var isFaceUp: Bool = true
    
    var body: some View {
        ZStack {
            let shape = RoundedRectangle(cornerRadius: 20)
            if isFaceUp {
            shape.fill().foregroundColor(.white)
            shape.strokeBorder(lineWidth: 4)
            Text(content).font(.largeTitle)
            } else {
                shape.fill()
            }
        }
        .onTapGesture {
            isFaceUp.toggle()
        }
    }
}


struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
            .preferredColorScheme(.dark)
        ContentView()
            .preferredColorScheme(.light)
    }
}