ContentView.swift

//
//  ContentView.swift
//  Shared
//
//  Created by Mohammad Azam on 7/21/20.
//

import SwiftUI

struct ContentView: View {
    
    @State private var degrees: Double = 0
    @State private var flipped: Bool = false
    
    var body: some View {
        CreditCard {
           
            VStack {
                Group {
                    if flipped {
                        CreditCardBack()
                    } else {
                        CreditCardFront()
                    }
                }
            }.rotation3DEffect(
                .degrees(degrees),
                axis: (x: 0.0, y: 1.0, z: 0.0)
            )
            
        }
        .onTapGesture {
            withAnimation {
                degrees += 180
                flipped.toggle()
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

CreditCard.swift

//
//  CreditCard.swift
//  CreditCardSwiftUI
//
//  Created by Mohammad Azam on 7/21/20.
//

import SwiftUI

struct CreditCard<Content>: View where Content: View {
    
    var content: () -> Content
    
    var body: some View {
        content()
    }
}


struct CreditCardFront: View {
    var body: some View {
        VStack {
            Text("FRONT").foregroundColor(Color.white)
        }.frame(width: 300, height: 200)
        .background(LinearGradient(gradient: Gradient(colors: [Color.red, Color.blue]), startPoint: .leading, endPoint: .trailing))
        .cornerRadius(10)
    }
}


struct CreditCardBack: View {
    var body: some View {
        VStack {
            Text("").foregroundColor(Color.white)
        }.frame(width: 300, height: 200)
        .background(LinearGradient(gradient: Gradient(colors: [Color.yellow, Color.blue]), startPoint: /*@START_MENU_TOKEN@*/.leading/*@END_MENU_TOKEN@*/, endPoint: /*@START_MENU_TOKEN@*/.trailing/*@END_MENU_TOKEN@*/))
        .cornerRadius(10)
    }
}


struct CreditCard_Previews: PreviewProvider {
    static var previews: some View {
        CreditCard<CreditCardFront>(content: { CreditCardFront() })
    }
}

can I ask u about this code?