enum ImplicitlyUnwrappedOptional<Wrapped> An optional type that allows implicit member access. Deprecated. Inheritance CustomDebugStringConvertible, CustomStringConvertible, ExpressibleByNilLiteral View Protocol Hierarchy → Import import Swift Cases case none The absence of a value. Typically written using the nil literal, nil. Declaration case some(Wrapped) The presence of a value, stored as Wrapped. Declaration Initializers init(_:) Creates an instance that stores the given value. Declaration init(_ some: Wrapped) init(nilLiteral:) Creates an instance initialized with nil. Do not call this initializer directly. It is used by the compiler when you initialize an Optional instance with a nil literal. For example: let i: Index! = nil Declaration init(nilLiteral: ()) Instance Variables var debugDescription: String A textual representation of this instance, suitable for debugging. Declaration var debugDescription: String { get } var description: String A textual representation of the value, or nil. Declaration var description: String { get }