ios - swift indexOf for [AnyObject] array -

trying index of array ([anyobject]). what's part i'm missing?

extension pageviewcontroller : uipageviewcontrollerdelegate {       func pageviewcontroller(pageviewcontroller: uipageviewcontroller, willtransitiontoviewcontrollers pendingviewcontrollers: [anyobject]) {         let controller: anyobject? = pendingviewcontrollers.first anyobject?         self.nextindex = self.viewcontrollers.indexof(controller) int?       }     } 

i have tried swift 1.2 approach:

func indexof<u: equatable>(object: u) -> int? {     (idx, objecttocompare) in enumerate(self) {       if let = objecttocompare as? u {         if object == {           return idx         }       }     }     return nil   } 

we need cast object we're testing uiviewcontroller, since know array of controllers holding uiviewcontrollers (and know uiviewcontrollers conform equatable.

extension pageviewcontroller : uipageviewcontrollerdelegate {     func pageviewcontroller(pageviewcontroller: uipageviewcontroller, willtransitiontoviewcontrollers pendingviewcontrollers: [anyobject]) {         if let controller = pendingviewcontrollers.first as? uiviewcontroller {             self.nextindex = self.viewcontrollers.indexof(controller)         }     } } 

the logic behind error in order indexof method compare object pass in, must compare them using == operator. equatable protocol specifies class has implemented function, indexof requires arguments conform to.

objective-c doesn't have same requirement, actual objective-c implementation ends meaning argument compared objects in array using isequal: method (which nsobject , therefore objective-c classes implement).