AnyHashable

struct AnyHashable

A type-erased hashable value.

The AnyHashable type forwards equality comparisons and hashing operations to an underlying hashable value, hiding its specific underlying type.

You can store mixed-type keys in dictionaries and other collections that require Hashable conformance by wrapping mixed-type keys in AnyHashable instances:

let descriptions: [AnyHashable: Any] = [
    AnyHashable("😄"): "emoji",
    AnyHashable(42): "an Int",
    AnyHashable(Int8(43)): "an Int8",
    AnyHashable(Set(["a", "b"])): "a set of strings"
]
print(descriptions[AnyHashable(42)]!)      // prints "an Int"
print(descriptions[AnyHashable(43)])       // prints "nil"
print(descriptions[AnyHashable(Int8(43))]!) // prints "an Int8"
print(descriptions[AnyHashable(Set(["a", "b"]))]!) // prints "a set of strings"
Inheritance CustomDebugStringConvertible, CustomReflectable, CustomStringConvertible, Equatable, Hashable View Protocol Hierarchy →
Import import Swift

Initializers

init(_:)

Creates a type-erased hashable value that wraps the given instance.

The following example creates two type-erased hashable values: x wraps an Int with the value 42, while y wraps a UInt8 with the same numeric value. Because the underlying types of x and y are different, the two variables do not compare as equal despite having equal underlying values.

let x = AnyHashable(Int(42))
let y = AnyHashable(UInt8(42))

print(x == y)
// Prints "false" because `Int` and `UInt8` are different types

print(x == AnyHashable(Int(42)))
// Prints "true"

base: A hashable value to wrap.

Declaration

init<H>(_ base: H)

Instance Variables

var base: Any

The value wrapped by this instance.

The base property can be cast back to its original type using one of the casting operators (as?, as!, or as).

let anyMessage = AnyHashable("Hello world!")
if let unwrappedMessage = anyMessage.base as? String {
    print(unwrappedMessage)
}
// Prints "Hello world!"

Declaration

var base: Any { get }
var customMirror: Mirror

The custom mirror for this instance.

If this type has value semantics, the mirror should be unaffected by subsequent mutations of the instance.

Declaration

var customMirror: Mirror { get }
var debugDescription: String

A textual representation of this instance, suitable for debugging.

Calling this property directly is discouraged. Instead, convert an instance of any type to a string by using the String(reflecting:) initializer. This initializer works with any type, and uses the custom debugDescription property for types that conform to CustomDebugStringConvertible:

struct Point: CustomDebugStringConvertible {
    let x: Int, y: Int

    var debugDescription: String {
        return "(\(x), \(y))"
    }
}

let p = Point(x: 21, y: 30)
let s = String(reflecting: p)
print(s)
// Prints "(21, 30)"

The conversion of p to a string in the assignment to s uses the Point type's debugDescription property.

Declaration

var debugDescription: String { get }
var description: String

A textual representation of this instance.

Calling this property directly is discouraged. Instead, convert an instance of any type to a string by using the String(describing:) initializer. This initializer works with any type, and uses the custom description property for types that conform to CustomStringConvertible:

struct Point: CustomStringConvertible {
    let x: Int, y: Int

    var description: String {
        return "(\(x), \(y))"
    }
}

let p = Point(x: 21, y: 30)
let s = String(describing: p)
print(s)
// Prints "(21, 30)"

The conversion of p to a string in the assignment to s uses the Point type's description property.

Declaration

var description: String { get }
var hashValue: Int

The hash value.

Declaration

var hashValue: Int { get }

Instance Methods

func hash(into:)

Hashes the essential components of this value by feeding them into the given hasher.

hasher: The hasher to use when combining the components of this instance.

Declaration

func hash(into hasher: inout Hasher)