protocol ExpressibleByNilLiteral A type that can be initialized using the nil literal, nil. nil has a specific meaning in Swift---the absence of a value. Only the Optional type conforms to ExpressibleByNilLiteral. ExpressibleByNilLiteral conformance for types that use nil for other purposes is discouraged. Inheritance View Protocol Hierarchy → Import import Swift Initializers init(nilLiteral:) Required Creates an instance initialized with nil. Declaration init(nilLiteral: ())