ios - Objective-C method 'controller:didChangeObject:atIndexPath:forChangeType:newIndexPath -

objective-c method 'controller:didchangeobject:atindexpath:forchangetype:newindexpath:' provided method 'controller(:didchangeobject:atindexpath:forchangetype:newindexpath:)' conflicts optional requirement method 'controller(:didchangeobject:atindexpath:forchangetype:newindexpath:)' in protocol 'nsfetchedresultscontrollerdelegate'

func controller(controller: nsfetchedresultscontroller, didchangeobject anobject: nsmanagedobject, atindexpath indexpath: nsindexpath?, forchangetype type: nsfetchedresultschangetype, newindexpath: nsindexpath?) {     if self.collectionview?.window == nil {         return     }      let change = nsmutabledictionary()      switch(type)     {     case .insert:         change[nsnumber(unsignedlong:type.rawvalue)] = newindexpath     case .delete:         change[nsnumber(unsignedlong:type.rawvalue)] = indexpath     case .update:         change[nsnumber(unsignedlong:type.rawvalue)] = indexpath     case .move:         change[nsnumber(unsignedlong:type.rawvalue)] = nsarray(objects: indexpath!, newindexpath!)     default:         break     }     self.objectchanges?.addobject(change) } 

it looks proper method signature is:

func controller(controller: nsfetchedresultscontroller, didchangeobject anobject: anyobject, atindexpath indexpath: nsindexpath?, forchangetype type: nsfetchedresultschangetype, newindexpath: nsindexpath?) {  } 

any easy way fix these problems allow xcode autocomplete method signature. then, replace method's signature auto generated signature. this, need type controller when defining method see list of methods match.