Question

如果我使用一对一，我可以显示所有相关的NSSet记录，但很多对很多人似乎都没有。

在我的segue上，我将体操运动员传给了一个VC，我希望在其中显示所有相关的会议，这些会议在一对多的情况下都能正常工作。

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {

        if let objs = fetchedResultsController.fetchedObjects where objs.count > 0 {

            let item = objs[indexPath.row] as! Gymnast

            performSegueWithIdentifier("displayMeets", sender: item)
        }
    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

        if segue.identifier == "displayMeets" {

            let vc = segue.destinationViewController as! SelectMeetVC

            vc.selectedGymnast = sender as? Gymnast
        }
    }

除非我注释掉NSPREDICATE

，否则我会崩溃

func loadFetchRequest() {

        self.fetchedResultsController = nil

        let fetchRequest = NSFetchRequest(entityName: "Meet")

        let sortDescriptor1 = NSSortDescriptor(key: "meetName", ascending: true)

        fetchRequest.sortDescriptors = [sortDescriptor1]

        //let filter = NSPredicate(format: "gymnasts.fullName == %@", "\(selectedGymnast.fullName!)")

        //fetchRequest.predicate = filter

        let controller = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: AD.managedObjectContext, sectionNameKeyPath: nil, cacheName: nil)

        controller.delegate = self

        fetchedResultsController = controller

        do {

            try fetchedResultsController.performFetch()

        } catch {

            fatalError("Error retrieving core data")
        }
    }

Answer 1

由于gymnasts关系为to-many，因此您需要修改谓词，以便在其Meet匹配的任何时选择gymnasts：

let filter = NSPredicate(format: "ANY gymnasts.fullName == %@", "\(selectedGymnast.fullName!)")

另请注意，无需使用fullName属性 - 您可以匹配Gymnast对象本身：

let filter = NSPredicate(format: "ANY gymnasts == %@", selectedGymnast)

如何与nsfetchedresultcontroller显示多对多的关系？

1 个答案: