Saving to Coredata Crashing - ios

Question

I have 2 classes, PhotoCollectionviewController and AddPhotoViewController. PhotoCollectionviewController is a subclass of FetchResultViewController. I was able to select a photo from library/camera ('AddPhotoViewController')when AddPhotoViewController was first in the navigationController and i segue to PhotoCollectionviewController. I have swapped the segues round so PhotoCollectionviewController is the first VC but i am now getting an error.
CoreData: error: Serious application error. Exception was caught during Core Data change processing. This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification. -[__NSCFData compare:]: unrecognized selector sent to instance 0x7fa5b2d78480 with userInfo (null)
PhotoCollectionViewController.h
#import "FetchResultViewController.h"
#import "PhotoCell.h"
#import "ViewController.h"
#import "AppDelegate.h"
#interface PhotoCollectionViewController : FetchResultViewController <UICollectionViewDelegate, UICollectionViewDelegateFlowLayout,UIGestureRecognizerDelegate,UICollectionViewDataSource>
#property (strong, nonatomic) NSMutableArray *photoArray;
#property (strong, nonatomic) IBOutlet UICollectionView *photoDiaryCollectionView;
#end
PhotoCollectionViewController.m
#import "PhotoCollectionViewController.h"
#import "Photo.h"
#interface PhotoCollectionViewController ()
#end
#implementation PhotoCollectionViewController
#synthesize fetchResultsController = _fetchResultsController;
- (void)viewDidLoad
{
[super viewDidLoad];
self.photoArray =[[NSMutableArray alloc]init];
self.photoDiaryCollectionView.delegate = self;
self.photoDiaryCollectionView.dataSource = self;
[NSFetchedResultsController deleteCacheWithName:#"Photos"];
[self.fetchResultsController performFetch:nil];
[self.photoDiaryCollectionView reloadData];
// [self getAllPhotos];
}
-(void)getAllPhotos
{
for (Photo *aPhoto in self.fetchResultsController.fetchedObjects)
{
UIImage *image = [UIImage imageWithData:aPhoto.photoData];
[self.photoArray addObject:image];
}
}
-(void) viewDidAppear:(BOOL)animated
{
[self.photoDiaryCollectionView reloadData];
}
- (NSFetchedResultsController*)fetchResultsController
{
if (_fetchResultsController == nil)
{
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:#"Photo"];
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:#"photoData" ascending:YES];
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
fetchRequest.sortDescriptors = #[sort];
_fetchResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest managedObjectContext:self.appDelegate.managedObjectContext sectionNameKeyPath:nil
cacheName:#"Photos"];
_fetchResultsController.delegate = self;
}
return _fetchResultsController;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
-(NSInteger) numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 1;
}
- (NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return self.fetchResultsController.fetchedObjects.count;
}
- (UICollectionViewCell *) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
PhotoCell *cell = (PhotoCell *)[collectionView dequeueReusableCellWithReuseIdentifier:#"PhotoCell" forIndexPath:indexPath];
Photo *photo = [self.fetchResultsController objectAtIndexPath:indexPath];
UIImage *image = [UIImage imageWithData:photo.photoData];
[self.photoArray addObject:[UIImage imageWithData:photo.photoData]];
[cell loadCell:image];
return cell;
}
- (CGFloat) collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
{
return 4;
}
- (CGFloat) collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
{
return 1;
}
- (void) collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
#end
AddPhotoViewController.h
#import "ViewController.h"
#import "Photo.h"
#import "AppDelegate.h"
#interface AddPhotoViewController : ViewController
#property (strong, nonatomic) IBOutlet UIImageView *photoImageView;
#property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;
- (IBAction)saveButtonPressed:(id)sender;
- (IBAction)takePhotoButtonPressed:(id)sender;
- (IBAction)pickFromLibraryButtonPressed:(id)sender;
#end
AddPhotoViewController.m
#import "AddPhotoViewController.h"
#interface AddPhotoViewController ()
#property (nonatomic,strong) UIImage *currentImage;
#end
#implementation AddPhotoViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)saveImage
{
AppDelegate *delegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
_managedObjectContext = [delegate managedObjectContext];
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:#"Photo"
inManagedObjectContext:self.managedObjectContext];
Photo *photos = (Photo*)[[NSManagedObject alloc]initWithEntity:entityDescription insertIntoManagedObjectContext:self.managedObjectContext];
NSData *imageData = UIImagePNGRepresentation(self.currentImage);
photos.photoData = imageData;
// [photos setPhotoData:imageData];
[delegate saveContext];
}
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
self.currentImage = [info objectForKey:UIImagePickerControllerOriginalImage];
[picker dismissViewControllerAnimated:YES completion:Nil];
self.photoImageView.image = self.currentImage;
}
- (IBAction)saveButtonPressed:(id)sender
{
[self saveImage];
// [self performSegueWithIdentifier:#"ImageSaved" sender:self];
}
- (IBAction)takePhotoButtonPressed:(id)sender
{
if (([UIImagePickerController isSourceTypeAvailable:
UIImagePickerControllerSourceTypeCamera] == NO))
return;
UIImagePickerController *mediaUI = [[UIImagePickerController alloc] init];
mediaUI.sourceType = UIImagePickerControllerSourceTypeCamera;
mediaUI.allowsEditing = NO;
mediaUI.delegate = self;
[self presentViewController:mediaUI animated:YES completion:nil];
}
- (IBAction)pickFromLibraryButtonPressed:(id)sender
{
if (([UIImagePickerController isSourceTypeAvailable:
UIImagePickerControllerSourceTypePhotoLibrary] == NO))
return;
UIImagePickerController *mediaUI = [[UIImagePickerController alloc] init];
mediaUI.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
mediaUI.allowsEditing = NO;
mediaUI.delegate = self;
[self presentViewController:mediaUI animated:YES completion:nil];
}
#end
I really can't see why this won't work, i've changed nothing except the position of the VC's in the navigationController

Answer 1

My guess is you have a NSManagedObjectContextObjectsDidChangeNotification somewhere and you are not removing the observer properly when its target is deallocated, so when a notification arrives, the observer tries to use the notification on the address of the former target where there is already a new object, that's why it shows the unrecognized selector message