Swift Protocol inheritance and protocol conformance issue

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You cannot implement a read-write property requirement of type BasePresenterProtocol? with a property of type DashboardPresenterProtocol?.

Consider what would happen if this were possible, and you upcast an instance of DashboardPresenter to DashboardViewProtocol. You would be able to assign anything that conforms to BasePresenterProtocol to a property of type DashboardPresenterProtocol? – which would be illegal.

For this reason, a read-write property requirement has to be invariant (although it’s worth noting that a readable-only property requirement should be able to be covariant – but this currently isn’t supported).

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