Just to add some more detail: the types in question, like NSJSONReadingOptions, are declared as NS_OPTIONS in Obj-C.
Before Swift 2
Prior to Swift 2, these were imported to Swift as RawOptionSetType, which required BitwiseOperationsType and NilLiteralConvertible. This allowed you to pass nil, and to combine values with operators a | b, a & ~b, etc.
/// Protocol for `NS_OPTIONS` imported from Objective-C
protocol RawOptionSetType : BitwiseOperationsType, NilLiteralConvertible { ...
protocol BitwiseOperationsType {
func &(lhs: Self, rhs: Self) -> Self
func |(lhs: Self, rhs: Self) -> Self
func ^(lhs: Self, rhs: Self) -> Self
prefix func ~(x: Self) -> Self
static var allZeros: Self { get }
}
Nowadays
In Swift 2 it's been generalized a bit more. These are now OptionSetType, which requires SetAlgebraType and RawRepresentable. (The underlying RawValue type may or may not be BitwiseOperationsType.)
public protocol OptionSetType : SetAlgebraType, RawRepresentable {
typealias Element = Self
public init(rawValue: Self.RawValue)
}
public protocol SetAlgebraType : Equatable, ArrayLiteralConvertible {
typealias Element
public init()
public func contains(member: Self.Element) -> Bool
public func union(other: Self) -> Self
public func intersect(other: Self) -> Self
public func exclusiveOr(other: Self) -> Self
// and more...
}
SetAlgebraType isn't NilLiteralConvertible anymore, but it is ArrayLiteralConvertible, so you can use [] instead of nil to mean "no options".
And you can combine multiple options in an array: options: [.MutableLeaves, .AllowFragments].
SetAlgebraType also has much more readable function names than those bitwise operators &, |, ^, etc:
public func contains(member: Self.Element) -> Bool
public func union(other: Self) -> Self
public func intersect(other: Self) -> Self
public func exclusiveOr(other: Self) -> Self
So you can use if jsonOptions.contains(.AllowFragments) { ... and such.
