Swift·Swift from optionals to SwiftUI

Setup and syntax

Use let, var, types and string interpolation in a Swift playground.

Beginner 12 min read Lesson 1 of 300 Challenge included

What you will be able to do

Prefer let by default.
Use \(value) for interpolation.
Use playgrounds for quick experiments.
Follow the Swift API design guidelines.

In plain English

Swift is expressive and type-safe. let declares a constant and var a variable. Type inference is strong; annotate when the type is not obvious. Use interpolation to build strings.

main.swiftSwift

let name = "Ada"
var count = 0
count += 1
print("Hello, \(name)! Count: \(count)")

Your turn

Interpolate a value

Easy

Print "Lesson: CSS" using a title constant.

SWIFT · starter

let title = "CSS"

Check your understanding before moving on.

Knowledge checkQuestion 1

Which keyword declares a constant?

Select an answer to continue

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