# init(_:radix:) Creates a new integer value from the given string and radix. ``` init?(_ text: S, radix: Int = 10) where S : StringProtocol ``` ## Parameters `text` The ASCII representation of a number in the radix passed as `radix`. `radix` The radix, or base, to use for converting `text` to an integer value. `radix` must be in the range `2...36`. The default is 10. ## Discussion The string passed as `text` may begin with a plus or minus sign character (`+` or `-`), followed by one or more numeric digits (`0-9`) or letters (`a-z` or `A-Z`). Parsing of the string is case insensitive. ``` let x = Int("123") // x == 123 let y = Int("-123", radix: 8) // y == -83 let y = Int("+123", radix: 8) // y == +83 let z = Int("07b", radix: 16) // z == 123 ``` If `text` is in an invalid format or contains characters that are out of bounds for the given `radix`, or if the value it denotes in the given `radix` is not representable, the result is `nil`. For example, the following conversions result in `nil`: ``` Int(" 100") // Includes whitespace Int("21-50") // Invalid format Int("ff6600") // Characters out of bounds Int("zzzzzzzzzzzzz", radix: 36) // Out of range ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)