A type-erased hashable value.
public struct AnyHashable {
public init<H>(_ base: H) where H : Hashable
public var base: Any { get }
public static func == (lhs: AnyHashable, rhs: AnyHashable) -> Bool
}
let descriptions: [AnyHashable: Any] = [
AnyHashable("??"): "emoji",
AnyHashable(42): "an Int",
AnyHashable(Int8(43)): "an Int8",
AnyHashable(Set(["a", "b"])): "a set of strings"
]
public struct Dictionary<Key, Value> where Key : Hashable
Key通常要指定一个确定的类型，如果类型不统一，向上抽象；向上无法解决问题，使用AnyHashable
AnyHashable类型擦除的原因：set和dictory需要指定一个确定的类型
原文：https://www.cnblogs.com/feng9exe/p/10524950.html