ios - errors creating a delegate from UISplitViewDetail to master in Swift -

swift / ios 8.2 trying set calculatorviewcontroller delegate target can data - seem setting wrong: "exc_bad_access (code:2)"

(in graphview.swift)

protocol calculatorviewdatasource: class {     func calculateyforxequals(sender: calculatorviewcontroller, currentx: cgfloat) ->cgfloat? }  class graphview: uiview {     weak var calculatorviewdatasource: calculatorviewdatasource?     //... } 

(in graphviewcontroller.swift)

class graphviewcontroller: uiviewcontroller {     @iboutlet weak var graphview: graphview! {         didset{             graphview.calculatorviewdatasource = self.view.superview?.superview calculatorviewcontroller         }     } // ... } 

(in calculatorviewcontroller.swift)

class calculatorviewcontroller: uiviewcontroller, calculatorviewdatasource{     // ... }  func calculateyforxequals(sender: calculatorviewcontroller, currentx: cgfloat) ->cgfloat? {     return nil } 

issues:

i crash "exc_bad_access (code:2)" error when try set delegate in graphviewcontroller... idea why?

i don't know how class calculatorviewcontroller level. here's storyboard:

-> splitviewcontroller - navigationcontroller - (master) calculatorviewcontroller               navigationcontroller - (detail) graphviewcontroller 

try this:

    var graphviewcontroller: graphviewcontroller?      private func setupsplitviewcontroller() {         let masternavigationcontroller: anyobject? = splitviewcontroller?.viewcontrollers.first         graphviewcontroller = masternavigationcontroller!.topviewcontroller as? graphviewcontroller         graphviewcontroller!.graphview.calculatorviewdatasource = self     }