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