Проблемы с NSFetchedResultsController, UICollectionView и BlockOperations
Я использую Flickr API загружать изображения, определенные для местоположения булавки, сброшенного пользователем. Я хочу, чтобы была возможность получить новый набор изображений, над которыми я сейчас работаю. Проблема в том, что это работает только один раз.
import UIKit
import CoreData
import MapKit
class PhotoCollectionViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource,
NSFetchedResultsControllerDelegate {
@IBOutlet weak var mapView:MKMapView!
@IBOutlet weak var photoCollectionView:UICollectionView!
@IBOutlet weak var backButton: UIBarButtonItem!
@IBOutlet weak var deleteButton: UIBarButtonItem!
@IBOutlet weak var noPhotosView: UIView!
var pinID = NSManagedObjectID()
var noPhotosBool = Bool()
var fetchedResults = [Photo]()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var shouldReloadCollectionView = true
var deletedIndexes = [IndexPath]()
var blockOperations = [BlockOperation]()
var deleteAllBool = Bool()
var fetchedResultsController: NSFetchedResultsController<NSFetchRequestResult>? {
didSet{
fetchedResultsController?.delegate = self
fetchResults()
self.photoCollectionView.reloadData()
}
}
override func viewDidLoad() {
noPhotosView.isHidden = true
super.viewDidLoad()
//photoCollectionView.setCollectionViewLayout(photoCollectionViewFlowLayout, animated: true)
var currentPin: Pin!
let fetchPin = NSFetchRequest<Pin>(entityName: "Pin")
let fetchedPins = try! context.fetch(fetchPin)
for pin in fetchedPins {
if pin.objectID == FlickrClient.Constants.Flickr.currentPinObjectID {
currentPin = pin
}
}
print(currentPin.latitude, currentPin.longitude)
let photoRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Photo")
let photoPredicate = NSPredicate(format: "pin = %@", currentPin)
let sort = NSSortDescriptor(key: "id", ascending: false)
photoRequest.sortDescriptors = [sort]
photoRequest.predicate = photoPredicate
fetchedResults = try! context.fetch(photoRequest) as! [Photo]
photoCollectionView?.delegate = self
photoCollectionView?.dataSource = self
let frc = NSFetchedResultsController(fetchRequest: photoRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
fetchedResultsController = frc
// Map Setup
self.mapView?.camera.altitude = CLLocationDistance(12000)
self.mapView?.centerCoordinate = CLLocationCoordinate2D(latitude: CLLocationDegrees(currentPin.latitude), longitude: CLLocationDegrees(currentPin.longitude))
let currentPinAnnotation = MKPointAnnotation()
currentPinAnnotation.coordinate.latitude = CLLocationDegrees(currentPin.latitude)
currentPinAnnotation.coordinate.longitude = CLLocationDegrees(currentPin.longitude)
self.mapView?.addAnnotation(currentPinAnnotation)
}
func fetchResults() {
if let fc = fetchedResultsController {
do {
try fc.performFetch()
}catch {
print(error)
}
}
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
@IBAction func dismissPhotoCollectionViewController(_ sender: Any) {
self.dismiss(animated: true) {
FlickrClient.Constants.Flickr.currentPinObjectID = nil
}
}
@IBAction func deletePhotos(_ sender: Any) {
var deletePhotos = [Photo]()
deleteAllBool = true
shouldReloadCollectionView = false
var indexsToDelete = [IndexPath]()
for section in 0..<photoCollectionView.numberOfSections {
for index in 0..<photoCollectionView.numberOfItems(inSection: section) {
indexsToDelete.append(IndexPath(item: index, section: section))
}
}
print(indexsToDelete.count)
print(fetchedResultsController?.fetchedObjects?.count)
for index in indexsToDelete {
deletePhotos.append(fetchedResultsController?.object(at: index) as! Photo)
}
for photo in deletePhotos {
fetchedResultsController?.managedObjectContext.delete(photo)
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let photo = fetchedResultsController?.object(at: indexPath)
fetchedResultsController?.managedObjectContext.delete(photo as! Photo)
}
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
if type == .insert {
print("insert@\(indexPath)")
if (photoCollectionView.numberOfSections) > 0 {
if photoCollectionView.numberOfItems(inSection: newIndexPath!.section) == 0 {
self.shouldReloadCollectionView = true
}else {
if deleteAllBool == true {
blockOperations.append(
BlockOperation(block: { [weak self] in
if let this = self {
this.photoCollectionView.insertItems(at: [newIndexPath!])
}
})
)
}else {
self.photoCollectionView.insertItems(at: [newIndexPath!])
}
}
} else {
self.shouldReloadCollectionView = true
}
}
else if type == .move {
print("moveItem@\(indexPath)")
//blockOperations.append(BlockOperation(block: { [weak self] in
// if let this = self {
// DispatchQueue.main.async {
self.photoCollectionView.moveItem(at: indexPath!, to: newIndexPath!)
// }
//}
//}))
}
else if type == .update {
print("updateItem@\(indexPath)")
//blockOperations.append(BlockOperation(block: { [weak self] in
// if let this = self {
// DispatchQueue.main.async {
self.photoCollectionView.reloadItems(at: [indexPath!])
//}
//}
//}))
}
else if type == .delete {
print("deleteItem@\(indexPath)")
// shouldReloadCollectionView = false
if photoCollectionView.numberOfItems(inSection: (indexPath?.section)!) == 1 {
self.shouldReloadCollectionView = true
}else {
if deleteAllBool == true {
blockOperations.append(BlockOperation(block: { [weak self] in
if let this = self {
//DispatchQueue.main.async {
this.photoCollectionView.deleteItems(at: [indexPath!])
//}
}
}))
}else {
self.photoCollectionView.deleteItems(at: [indexPath!])
}
}
}
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange sectionInfo: NSFetchedResultsSectionInfo, atSectionIndex sectionIndex: Int, for type: NSFetchedResultsChangeType) {
if type == .insert {
//blockOperations.append(BlockOperation(block: { [weak self] in
// if let this = self {
// DispatchQueue.main.async {
self.photoCollectionView.insertSections(NSIndexSet(index: sectionIndex) as IndexSet)
// }
//}
//}))
}
else if type == .update {
// blockOperations.append(BlockOperation(block: { [weak self] in
// if let this = self {
// DispatchQueue.main.async {
self.photoCollectionView.reloadSections(NSIndexSet(index: sectionIndex) as IndexSet)
// }
// }
// }))
}
else if type == .delete {
// blockOperations.append(BlockOperation(block: { [weak self] in
// if let this = self {
//DispatchQueue.main.async {
self.photoCollectionView.deleteSections(NSIndexSet(index: sectionIndex)as IndexSet)
//}
// }
// }))
}
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
print("controller Did Change Content", self.shouldReloadCollectionView)
// self.shouldReloadCollectionView = false
if self.shouldReloadCollectionView == true {
//DispatchQueue.main.async {
self.photoCollectionView.reloadData()
//}
}else {
self.photoCollectionView.performBatchUpdates({ () -> Void in
for operation: BlockOperation in self.blockOperations {
operation.start()
}
}, completion: {(finished) -> Void in
self.shouldReloadCollectionView = true
self.blockOperations.removeAll(keepingCapacity: false)
if self.photoCollectionView.numberOfItems(inSection: 0) < 1 {
FlickrClient.sharedInstance().getPhotosFromFlickr(lat: Float(self.mapView.annotations[0].coordinate.latitude), lon: Float(self.mapView.annotations[0].coordinate.longitude)) { (success, error) in
if success != true {
print(error)
}else {
//try! self.fetchedResultsController?.performFetch()
//self.photoCollectionView.reloadData()
}
}
}
})
}
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return (fetchedResultsController?.sections?.count)!
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
let sectionData = fetchedResultsController?.sections![section]
return (sectionData?.numberOfObjects)!
}
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
let reuseId = "pin"
var pinView = mapView.dequeueReusableAnnotationView(withIdentifier: reuseId) as? MKPinAnnotationView
if pinView == nil {
pinView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
pinView!.canShowCallout = true
pinView!.pinTintColor = .red
pinView!.animatesDrop = true
pinView!.rightCalloutAccessoryView = UIButton(type: .detailDisclosure)
pinView!.rightCalloutAccessoryView?.backgroundColor = UIColor.cyan
}
else {
pinView!.annotation = annotation
}
return pinView
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = photoCollectionView?.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! photoCollectionViewCell
cell.photoActivityIndicator.isHidden = false
cell.photoActivityIndicator.startAnimating()
cell.photoActivityIndicator.hidesWhenStopped = true
cell.photoImageView.image = #imageLiteral(resourceName: "placeholder")
let photo = fetchedResultsController?.object(at: indexPath) as! Photo
if photo.imageData != nil {
cell.photoImageView.image = UIImage(data: photo.imageData! as Data)
cell.photoActivityIndicator.stopAnimating()
}else {
DispatchQueue.main.async {
let session = URLSession.shared
let request = URLRequest(url: URL(string: photo.imageURL!)!)
let task = session.dataTask(with: request) { (data, response, error) in
if error != nil {
print(error)
}else {
photo.imageData = data! as NSData
cell.photoImageView.image = UIImage(data: photo.imageData! as Data)
cell.photoActivityIndicator.stopAnimating()
}
}
task.resume()
}
}
return cell
}
}
Выше мой код для collectionViewController и соответствующий NSFetchedResultsController, Моя проблема в первый раз IBActiondeletePhotos() называется, все работает отлично. Фотографии удалены из CoreDataэто вызывает NSFetchedResultsController реализовать изменения в collectionView, а затем сделать еще один звонок Flickr чтобы получить другой набор изображений, связанных с местоположением этого вывода. Второй раз IBAction называется, фотографии удаляются из CoreData, но NSFetchedResultsController"s didChangeContent не звонит Flickr, Итак, мой вопрос, что отличается между первым удалением и вторым, что делает его таким NSFetchedResultsController не будет звонить Flickr?