The README says:
Avoid introducing new @optional properties with a nullable type, since in this case Swift does not provide a mechanism for differentiating between "property not implemented" and "property implemented and its value is nil". Use a getter method in this situation instead.
I'm not actually sure this is true — you can still do the responds(to:) check explicitly in Swift
The README says:
I'm not actually sure this is true — you can still do the
responds(to:)check explicitly in Swift