CODEWITHSUNDEEP
swiftcore-datansfetchedresultscontroller
Lester
Lester

Reputation: 731

How to reload fetchedResultsController on viewWillAppear?

How to reload fetchedResultsController on viewWillAppear? because I want to reload the table view and data after I dismiss a pop out view controller.

This fetch controller seem only run when the view is load because It keep the old data. How to run or refresh the fetch controller when the view is appear?

var fetchedResultsController: NSFetchedResultsController<Record> {
    if _fetchedResultsController != nil {
        return _fetchedResultsController!
    }

    let fetchRequest: NSFetchRequest<Record> = Record.fetchRequest()
    fetchRequest.fetchBatchSize = 20
    let accBtn = UserDefaults().value(forKey: "BtnName") as! String
    let sortDescriptor = NSSortDescriptor(key: "createdAt", ascending: false)
    fetchRequest.sortDescriptors = [sortDescriptor]
    fetchRequest.predicate = NSPredicate(format: "%K == %@", "accountbook" , "\(accBtn)")
    let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: "createdAt", cacheName: nil)
    aFetchedResultsController.delegate = self
    _fetchedResultsController = aFetchedResultsController

    do {
        try _fetchedResultsController!.performFetch()
    } catch {
        let nserror = error as NSError
        fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
    }

    return _fetchedResultsController!
}

var _fetchedResultsController: NSFetchedResultsController<Record>? = nil

func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    self.tableView.beginUpdates()
}

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange sectionInfo: NSFetchedResultsSectionInfo, atSectionIndex sectionIndex: Int, for type: NSFetchedResultsChangeType) {
    switch type {
    case .insert:
        self.tableView.insertSections(IndexSet(integer: sectionIndex), with: .fade)
    case .delete:
        self.tableView.deleteSections(IndexSet(integer: sectionIndex), with: .fade)
    default:
        return
    }
}

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
    switch type {
    case .insert:
        tableView.insertRows(at: [newIndexPath!], with: .fade)
    case .delete:
        tableView.deleteRows(at: [indexPath!], with: .fade)
    case .update:
        self.configureCell(tableView.cellForRow(at: indexPath!)! as! DashboardCell, withRecordItem: anObject as! Record)
    case .move:
        tableView.moveRow(at: indexPath!, to: newIndexPath!)
    }
}

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    self.tableView.endUpdates()
}

Upvotes: 2

Views: 1224

Answers (1)

Puneet Sharma
Puneet Sharma

Reputation: 9484

If your ViewController is in memory when you change the data in the managed object context, the fetched result controller delegates should work.

In your current implementation, you are updating the tableview when each change is made and its not always advisable to do it. I guess you need to digress and implement only didChangeContent and reloadData on it

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    self.tableView.reloadData()
}

Upvotes: 3

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