ios - Downcast from Any to a protocol -

ios - Downcast from Any to a protocol -

i have next code. how can resolve error in lastly line?

protocol animal { func walk() } struct cat: animal { func walk() {} init() { } } var obj: = cat() var cat = obj animal // error: cannot downcast unrelated type animal

update: has been fixed in swift 1.2+ (xcode 6.3+). xcode 6.3 beta release notes say:

dynamic casts (“as!", “as?" , “is”) work swift protocol types, long have no associated types.

you can check protocol conformance (which includes is, as, , as?) @objc protocol. animal not @objc.

see checking protocol conformance section of swift book.

note

you can check protocol conformance if protocol marked @objc attribute

ios swift