ios - NSFetchedResultsController count in Swift -

i novice swift developer coming objective-c background.

i have following code:

class kpcoredataresultscontroller: nsobject, nsfetchedresultscontrollerdelegate {      var fetchedresultscontroller: nsfetchedresultscontroller      let managedobjectcontext = (uiapplication.sharedapplication().delegate as! appdelegate).managedobjectcontext!      let entityname: nsstring     var delegate: kpcoredataresultsdelegate?      var predicate: nspredicate {         {             return fetchedresultscontroller.fetchrequest.predicate!         }         set {             fetchedresultscontroller.fetchrequest.predicate = newvalue                         {                 try fetchedresultscontroller.performfetch()             } catch {                 print(error)             }         }     }     var sortdescriptor: nssortdescriptor!     var count: nsinteger {         return (fetchedresultscontroller.sections!.first!).numberofobjects     }      init(entityname: string, predicate: nspredicate, sortdescriptor: nssortdescriptor) {         self.entityname = entityname         let fetchrequest = nsfetchrequest(entityname: entityname)         fetchrequest.predicate = predicate         fetchrequest.sortdescriptors = [sortdescriptor]         fetchedresultscontroller = nsfetchedresultscontroller(fetchrequest: fetchrequest, managedobjectcontext: managedobjectcontext, sectionnamekeypath: nil, cachename: nil)         super.init()     } } 

inside of custom core data results controller file simplify accessing coredata stuff. when call results controller's count property table view (numberofrowsinsection), app crashes saying:

fatal error: unexpectedly found nil while unwrapping optional value

here table view code:

override func tableview(tableview: uitableview, numberofrowsinsection section: int) -> int {     return accountcontroller.count } 

basically, code above giving error - using !'s wrong? or happening here?

try

  return fetchedresultscontroller.sections![section].numberofobjects