ios - Pass a class to other class SWIFT -

i pass class class b , call method backwards class a. i'm not sure if understand me.

class a:

    public func showalertfor()         {             let secondcontroller = secondcontroller()             var alert : uialertcontroller = secondcontroller.showalertfortranslate( **????** )             self.presentviewcontroller(alert, animated: true, completion: nil)         }      public func dosomething     {           println("dosomething")     } 

class b: (second controller)

public func showalertfortranslate( **????** ) {  **????**.dosomething() // other stuff } 

this how call function class b , b a:

class a{      func foo(){         println("a foo");     }      func tellbtocallfoo(){         var myb = b()         myb.foothea(self);     } }  class b{      func foothea(mya : a){         mya.foo();     } }   var mya = a(); mya.tellbtocallfoo() 

you can work protocols

protocol mycustomprotocol {     func mycallbackfunction(); }  class : mycustomprotocol{      func mycallbackfunction(){         println("i a")     } }  class b : mycustomprotocol{      func mycallbackfunction(){         println("i b")     } }  class c{      func dosomethingwithmycustomprotocol(mcp : mycustomprotocol){         mcp.mycallbackfunction();     } }  var mya = a(); var myb = b(); var myc = c();  myc.dosomethingwithmycustomprotocol(mya); myc.dosomethingwithmycustomprotocol(myb);  //output:  //i //i b