let vs var, type inference, literals, tuples
Understand let vs var, type inference, numeric/string literals, and tuples for grouping values.
let vs var, type inference, literals, tuples is a free Swift Academy lesson on CoddyKit. This is lesson 1 of 3. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the Swift Academy learning path, and your progress syncs across the web and the CoddyKit app. The Swift Academy course includes 3 lessons in total.
Intro
Swift values can be declared with let (constant) or var (variable). Type inference makes code concise.
let vs var
Use let for constants, var for mutable variables.
// Constant cannot change
let pi = 3.14
// pi = 3.14159 // error: cannot assign to value: 'pi' is a 'let' constant
// Variable can change
var counter = 0
counter += 1
print("counter =", counter)
Type inference
Swift infers types automatically, reducing boilerplate.
// Type inferred as Int
let a = 10
// Type inferred as Double
let b = 2.5
// Type inferred as String
let msg = "Swift"
print(a, b, msg)
Literals
Swift supports literals for values:
- Numbers:
42,3.14 - Strings:
"Hi" - Booleans:
true,false
Tuples
Tuples group multiple values, accessed by index or name.
// Group values together
let person = ("Ada", 28)
print("Name: \(person.0), Age: \(person.1)")
// Named tuple elements
let user = (name: "Alan", age: 35)
print("User name = \(user.name), age = \(user.age)")
Best practice
Use let whenever possible. It signals intent, avoids accidental changes, and enables compiler optimizations.
Constant keyword
Quick check: What keyword defines a constant?
Recap
Recap: Use let for constants, var for variables, rely on type inference, use literals, and group values with tuples.
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Frequently Asked Questions
Is the “let vs var, type inference, literals, tuples” lesson free?
Yes — any 3 lessons of the Swift Academy learning path, including “let vs var, type inference, literals, tuples”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The Swift Academy course includes 3 lessons in total.
What will I learn in “let vs var, type inference, literals, tuples”?
Understand let vs var, type inference, numeric/string literals, and tuples for grouping values. You practise Swift Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Swift Academy?
No prior experience is required. Swift Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 3.
How long does the “let vs var, type inference, literals, tuples” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Swift Academy lesson?
Yes. Every Swift Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- let vs var, type inference, literals, tuples
- Core types: numbers, Bool, String, Character
- Optionals intro: ?, nil, if let, guard let, ??