True Or False State

Part of the Introduction to SwiftUI section of Coddy's Swift journey. Lesson 21 of 50.

State can be a Bool. toggle() flips it between true and false:

@State private var isOn = false

Button("Switch") {
    isOn.toggle()
}

The ternary operator picks a value from the state, so one view can show two versions:

Text(isOn ? "Light is on" : "Light is off")
    .foregroundStyle(isOn ? .yellow : .gray)

isOn ? a : b gives a when isOn is true and b otherwise. After each tap, the body runs again and both the text and the color follow the new value.

Challenge

Easy

Make the lamp work. Tapping Switch should flip isOn, and the text should read Light is on when isOn is true and Light is off when it is false.

Try it yourself

import SwiftUI

@main
struct CoddyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Introduction to SwiftUI

1Introduction

What Is SwiftUI The App File

4Modifiers

Padding Backgrounds Modifier Order Frames And Shapes Recap - Badge Maker

7Lists

ForEach Identifiable Items List Adding Items Recap - Shopping List

10Project - Coddy Coffee

Project Overview Drink Screens

Choose A Size

Quantity And Total

Place The Order

2Showing Content

Text Views Numbers In Text Fonts Colors SF Symbols Recap - Price Tag

5State & Buttons

Buttons The @State PropertyTrue Or False StateConditional Views Recap - Score Keeper

8Navigation

NavigationStack NavigationLink Passing Data Sheets And Alerts Recap - Plant Guide

11Final Challenges

Tip Calculator To-Do List True Or False Game

3Stacks & Layout

VStack HStack Alignment And Spacing Spacer And ZStack Recap - Weather Card

6User Input

TextField Toggle Stepper And Slider Picker Recap - Order Form

9Sharing Data

The @Binding Property Observable Objects Environment Objects Recap - Step Counter

Practice on your own: Swift playground