ios - Difficulty configuring NSFetchedResultsController in Swift 3 -


i'm refactoring existing project swift 2 swift 3. has been straightforward until got refactoring core data. i'm able create managed objects , persist them in managedobjectcontext, i'm having difficulty getting nsfetchedresultscontroller work. took @ this post, it's not getting me across finish line.

after importing records json, verify there objects in managedobjectcontext following code:

func recordcount() -> int {     let context = (uiapplication.shared.delegate as! appdelegate).persistentcontainer.viewcontext     let fetchrequest: nsfetchrequest<nsfetchrequestresult> = nsfetchrequest(entityname: "myentity")     let count = try! context.count(for: fetchrequest)     return count }

when create fetchedresultscontroller, i'm running trouble. code doesn't crash, doesn't return nsmanagedobjects despite there being objects match search.

here's how i'm creating nsfetchedresultscontroller in uiviewcontroller.

class myviewcontroller: uiviewcontroller, uitableviewdelegate, uitableviewdatasource, nsfetchedresultscontrollerdelegate {     // set on prior viewcontroller before segue.     // i've verified it's not nil     var selectedequipmentstring: string?      let managedobjectcontext = (uiapplication.shared.delegate as! appdelegate).persistentcontainer.viewcontext      lazy var fetchedresultscontroller: nsfetchedresultscontroller<myentity> = {         // i've tried altering syntax of fetchrequest         // let fetchrequest: nsfetchrequest<myentity> = myentity.fetchrequest()         let fetchrequest: nsfetchrequest<nsfetchrequestresult> = nsfetchrequest(entityname: "myentity")         let sortdescriptor = nssortdescriptor(key: "generalarea", ascending: true)         fetchrequest.sortdescriptors = [sortdescriptor]         fetchrequest.predicate = nspredicate(format: "equipmentdescription == %@", self.selectedequipmentstring!)         let frc: nsfetchedresultscontroller<myentity> = nsfetchedresultscontroller(fetchrequest: fetchrequest as! nsfetchrequest<myentity>, managedobjectcontext: self.managedobjectcontext, sectionnamekeypath: "generalarea", cachename: nil)         frc.delegate = self         return frc     }()      // mark: - view lifecycle methods (abbreviated)     override func viewdidload() {         super.viewdidload()         // i've tried moving call viewwillappear , viewdidappear without success         fetchobjectsfrommanagedobjectcontext()     }      // mark: - core data methods (abbreviated)     func fetchobjectsfrommanagedobjectcontext() {         {             try fetchedresultscontroller.performfetch()         } catch {             print("error: \(error)")             return         }         print ("there \(fetchedresultscontroller.fetchedobjects!.count) returned fetchobjectsfrommanagedobjectcontext")     } }

this code doesn't crash, doesn't return records fetchrequest. able force crash typo in predicate, without typo there no objects returned despite objects match predicate.

i welcome suggestions re: mistake is. rest assured knowing startlingly silly oversight on part. thank reading.

your nsfetchrequest should have type nsfetchrequest<myentity>, specify nsfetchrequest<nsfetchrequestresult>. try changing , let me know if helps or not


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