Variables & Constants in Swift
From the Swift cheat sheet · Getting Started · verified Jul 2026
Variables & Constants
Declaration and initialization
swift
var mutableVariable = "Can change"
let immutableConstant = "Cannot change"
// Type annotations
var explicitString: String = "Hello"
let explicitInt: Int = 42
// Type inference
let inferredBool = true // Bool💡 Use `let` by default, only use `var` when you need mutability
⚡ Swift has strong type inference - explicit types often unnecessary
📌 Constants can be set once and only once, even after declaration
🟢 Computed properties calculate their value each time they are accessed
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