Swift, how to implement Hashable protocol based on object reference?

Question

I've started to learn swift after Java. In Java I can use any object as a key for HashSet, cause it has default hashCode and equals based on object identifier. How to achieve the same behaviour in Swift?

Answer 1

If you are working with classes and not structs, you can use the ObjectIdentifier struct. Note that you also have to define == for your class in order to conform to Equatable (Hashable requires it). It would look something like this:

class MyClass: Hashable { 

    static func == (lhs: MyClass, rhs: MyClass) -> Bool {
        ObjectIdentifier(lhs) == ObjectIdentifier(rhs)
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(ObjectIdentifier(self))
    }

}