Headerdoc with delegate Protocols - Swift and xcode 7.2 -

i have defined protocol , added headerdoc documentation method in protocol. appears correctly when option+click method:

however, when option+click implementation within controller implements protocol, documentation not showing up:

my expectation documentation wrote protocol show in controller, similar documentation apple:

how protocol documentation visible elsewhere?

if document protocol's method implementation within protocol extension, documentation visible within type conforms protocol.

if omit extension's documentation, cando documentation protocol doesn't show anywhere else protocol itself, noticed.

protocol doable {     ///     func cando() }  extension doable {     ///     func cando() {         print("did it!")     } }  struct task: doable {     init() {         cando()     } }