Swift type checker rejects protocol that has a class requirement as a class type

Question

I am trying to generalize a type, so I can mock the class it is based on. This means I want to switch from a concrete implementation to a protocol.

The original class looks like this:

open class WebSocket : NSObject, StreamDelegate, WebSocketClient, WSStreamDelegate { ... }
    ...
}

I want to replace this with this protocol, that WebSocket is already extending:

public protocol WebSocketClient : AnyObject {
    ...
}

This means I am replacing

public class RxWebSocketDelegateProxy: DelegateProxy<WebSocket, NSObjectProtocol>, ... {
    ...
}

with

public class RxWebSocketDelegateProxy: DelegateProxy<WebSocketClient, NSObjectProtocol>, ... {
    ...
}

All of this seems easy enough — WebSocketClient provides all the functionality that is needed here. Surprisingly, I am receiving the error message

'DelegateProxy' requires that 'WebSocketClient' be a class type

I am not sure what I am missing here and would appreciate pointers!

This looks like its due to [protocols not conforming to themselves](https://stackoverflow.com/a/43408193/2976878) — Hamish, Oct 27 '18 at 11:18

score 0 · Accepted Answer · answered Oct 27 '18 at 02:01

0

Try with @objc like below:

@objc public protocol WebSocketClient : AnyObject {
    ---
}

answered Oct 27 '18 at 02:01

Razib Mollick

1 Answers1