Swift Optionals

An optional type, written Int?, either holds a value or holds nil. Int("42") returns an Int? because the text may not be a number. Swift forces you to deal with the possibility of nil before using the value.

let values = ["42", "x7"]
for text in values {
    if let number = Int(text) {
        print("number \(number + 1)")
    } else {
        print("not a number: \(text)")
    }
}