protocol ExpressibleByBooleanLiteral A type that can be initialized with the Boolean literals true and false. Conforming Types Bool Associated Types associatedtype BooleanLiteralType Bool, DarwinBoolean, ObjCBool, and WindowsBool are treated as Boolean values. Expanding this set to include types that represent more than simple Boolean values is discouraged. To add ExpressibleByBooleanLiteral conformance to your custom type, implement the init(booleanLiteral:) initializer that creates an instance of your type with the given Boolean value. Initializers init init(booleanLiteral:) Required Creates an instance initialized to the given Boolean value. Do not call this initializer directly. Instead, initialize a variable or constant using one of the Boolean literals true and false. For example: let twasBrillig = true In this example, the assignment to the twasBrillig constant calls this Boolean literal initializer behind the scenes. Parameter value: The value of the new instance. Declaration init(booleanLiteral value: Self.BooleanLiteralType)