Swift protocol property in protocol - Candidate has non-matching type

Question

I have a protocol (ProtocolA) containing a single property conforming to a second protocol (ProtocolB).

public protocol ProtocolA {        
    var prop: Prot         


        

Answer 1

You need to declare a typealias of the type that conforms to the other protocol. The way you did it is that prop has to be exactly of type ProtocolB, but you don't actually want that, you want a type that conforms to it instead.

protocol ProtocolA {
    typealias Prop : ProtocolB
    var prop: Prop? { get }
}

protocol ProtocolB {}


class ClassA : ProtocolA {
    var prop: ClassB?
}

class ClassB : ProtocolB {}