ios - Why does the type not conform to protocol? -

let's have following piece of code:

protocol itemview {      var image: uiimage? { set } }   class basecontroller<t: uiview t: itemview>: uiviewcontroller {      var itemview = t() }  class concreteitemcontroller: basecontroller<uiimageview> {  } 

for basecontroller getting error message saying "type "uiimageview" not conform protocol "itemview"".

but why?

same error message shows when instead:

 typealias concreteitemcontroller = basecontroller<uiimageview>  

i missing here...why uiimageview not conform itemview protocol? has optional image property..so where's problem?

uiimageview not declare conforms itemview. because swift strictly typed language, doesn't infer conformance protocols, types incidentally conform. like:

protocol itemview {      var image: uiimage? { set } }  class basecontroller<t: uiview t: itemview>: uiviewcontroller {      var itemview = t() }  extension uiimageview: itemview {}  class concreteitemcontroller: basecontroller<uiimageview> {  }