Swift Language Optionals
Introduction
“ An optional value either contains a value or contains nil to indicate that a value is missing”
Excerpt From: Apple Inc. “The Swift Programming Language (Swift 3.1 Edition).” iBooks. https://itun.es/us/k5SW7.l
Basic optional use cases include: for a constant (let), use of an optional within a loop (if-let), safely unwrapping an optional value within a method (guard-let), and as part of switch loops (case-let), defaulting to a value if nil, using the coalesce operator (??)
Syntax
- var optionalName: optionalType? // declare an optional type, defaults to nil
- var optionalName: optionalType? = value // declare an optional with a value
- var optionalName: optionalType! // declare an implicitly unwrapped optional
- optional! // force unwrap an optional
Remarks
For more information about optionals, see The Swift Programming Language.
