[iOS] Swift introduction

Limited resources:

• Power limitation
• CPU limitation

// ContentView.swift
import SwfitUI

struct ContentView: View {
    var body: some View {
        // return can be omitted
        return HStack(content: { // return a view with contents horizontally on one layer
            ForEach(0..<4, content: { index in // return an array of View, from 0 to 4(not including 4)
                ZStack(content: { // return a view with contents on top of each other
                    RoundedRectangle(cornerRadius: 10.0).fill(Color.white)
                    RoundedRectangle(corderRadius: 10.0).stroke(lineWidth: 3)
                    Text("test")
                })
            })
        })
            .padding() // will add padding to everything in ZStack
            .foregroundColor(Color.orange) // Will change color of everything in ZStack
            .font(Font.largeTitle)
    }
}

• return can be omitted
• If a function only has one argument, it can be omitted, and also the parenthesis can be omitted

struct ContentView: View {
    var body: some View {
        // return can be omitted
        return HStack { // return a view with contents horizontally on one layer
            ForEach(0..<4) { index in // return an array of View, from 0 to 4(not including 4)
                CardView(isFaceUp: false)
            }
        }
            .padding() // will add padding to everything in ZStack
            .foregroundColor(Color.orange) // Will change color of everything in ZStack
            .font(Font.largeTitle)
    }
}

struct CardView: View {
    var isFaceUp: Bool;

    var body: some View {
        ZStack { // return a view with contents on top of each other
            if isFaceUp {
                RoundedRectangle(cornerRadius: 10.0).fill(Color.white)
                RoundedRectangle(corderRadius: 10.0).stroke(lineWidth: 3)
                Text("test")
            } else {
                RoundedRectangle(cornerRadius: 10.0).fill()
            }
            
        }
    }
}