Can't fix hashability for a class derived from NSObject

Question

final class Foo: NSObject, NSFileProviderItem
{
    public func hash(into hasher: inout Hasher)
    {
        hasher.combine(itemIdentifier)
    }
}

yields swift compiler errors:

Overriding non-open instance method outside of its defining module

Overriding declarations in extensions is not supported

Is there a way to fix NSObject hashability? I get duplicates of Foo instances in Sets which is precisely what I want to avoid.

Possible duplicate of https://stackoverflow.com/q/33319959/1187415: NSObject subclasses must override `hash` and `isEqual:` — Martin R, Jul 25 '19 at 16:30

score 4 · Answer 1 · answered Jul 25 '19 at 16:52

Found the fix here:

public override var hash: Int {
    var hasher = Hasher()
    hasher.combine(itemIdentifier)
    return hasher.finalize()
}

1 Answers1