Casting a generic class

Question

I have a class of the following type:

class OptionViewModel<T: SelectableOption>: ViewModel

At some other point I need to be able to do something like the following:

func configure(viewModel: ViewModel) {
  guard let model = model as? OptionViewModel else { return }
}

I don't care at this point what the generic type is (only that it conforms to the protocol) but I can't get this line to compile due to having to supply a concrete type here (which I don't know - currently I have 4 possibilities).

Generic parameter 'T' could not be inferred in cast to 'OptionViewModel'

I'm looking for any suggestions on how to restructure this, or get around my issue. Thanks!

"I don't care at this point what the generic type is (only that it conforms to the protocol)" I'm not sure what protocol you are talking about here. `OptionViewModel` is not a protocol. Do you want to check for `ViewModel` instead (which presumably is a protocol)? — Sweeper, Jul 04 '21 at 06:27
"currently I have 4 possibilities" - this is the problem. The compiler doesn't know which one you mean either `OptionViewModel` and `OptionViewModel` are unrelated types as far as the compiler is concerned. Even thought they are both specialisations off the same generic type they are not related in the way superclass/subclasses are. See https://stackoverflow.com/questions/41976844/swift-generic-coercion-misunderstanding and https://stackoverflow.com/questions/62285398/convert-concrete-type-having-generic-in-class-signature-swift — Paulw11, Jul 04 '21 at 06:31

Casting a generic class

0 Answers0