Swift Optionals

Swift Optionals

Represent missing values safely with optionals, and unwrap them with ??, if let, or guard let.

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What Are Optionals?

An optional is a type that can hold either a value or nil (no value).

Use ? to declare an optional, and nil-coalescing (??) or binding (if let) to safely read it.

Syntax:

• var x: String?
• x ?? "default"
• if let v = x { ... }
• guard let v = x else { return }

Example

var nickname: String? = nil
print(nickname ?? "(none)")

nickname = "Ace"
if let name = nickname {
  print(name)
}

This example prints a default using ?? and unwraps an optional safely with if let.

Tip: Use guard let inside functions to early-exit on missing values.

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Guard Let

Use guard let for early exit when required values are missing.

Example

func greet(_ input: String?) {
  guard let name = input else {
print("Missing name")
return
  }
  print("Hello, \(name)")
}

greet(nil)
greet("Swift")