iOS UITableView with core data crash after delete - ios

Question

I'm working on an iOS app written in Objective-C and I have table view with many records from Core data. When I delete one record the row is deleted from Core data but the app is giving me an error:
-[_PFArray removeObjectAtIndex:]: unrecognized selector sent to instance 0x7fbf5be5e6b0
I have tried many times to change this but it still crashes the app or the table view is not updated after deletion.
This is my header file:
#import <UIKit/UIKit.h>
#include "Notes.h"
#interface ShowClassNote : UIViewController<UITabBarDelegate,UITableViewDataSource>
// get moodle id from segue
#property(strong,nonatomic)NSString*moodeleID;
#property(strong,nonatomic)NSString*moodleName;
#property(strong,nonatomic)NSString*content;
#property (nonatomic, strong) NSMutableArray *fetchedObjects;
#property(strong)NSManagedObjectContext*passThis;
#property(strong,nonatomic)NSString*dataForSend;
#property(strong,nonatomic)NSArray*noteID;
#property(strong,nonatomic)NSArray*noteTitle;
#property(strong,nonatomic)NSArray*insertDates;
#property(strong,nonatomic)NSArray*noteContent;
#property (weak, nonatomic) IBOutlet UILabel *classTitleLable;
#property (weak, nonatomic) IBOutlet UITableView *allNotes;
#end
and this is my implementation file:
#import "ShowClassNote.h"
#import "Subjects.h"
#import "NewClassNote.h"
#import "Notes.h"
#import "AllClassNotesCell.h"
#interface ShowClassNote ()
#end
#implementation ShowClassNote
- (void)viewDidLoad {
[super viewDidLoad];
id delegate =[[UIApplication sharedApplication]delegate];
NSError*error=nil;
NSManagedObjectContext *context = [delegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Notes"
inManagedObjectContext:context];
NSPredicate * predicate =[NSPredicate predicateWithFormat:[NSString stringWithFormat:#"moodleCode=='%#'",self.moodeleID]];
[fetchRequest setPredicate:predicate];
[fetchRequest setEntity:entity];
self.fetchedObjects = [[NSMutableArray alloc]initWithObjects:[context executeFetchRequest:fetchRequest error:&error], nil];
// self.fetchedObjects =(NSMutableArray *) [context executeFetchRequest:fetchRequest error:&error];
// NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
self.noteTitle =[[[NSArray alloc]initWithArray:_fetchedObjects]valueForKey:#"title"];
self.insertDates =[[[NSArray alloc]initWithArray:_fetchedObjects]valueForKey:#"insertDate"];
self.noteContent =[[[NSArray alloc]initWithArray:_fetchedObjects]valueForKey:#"content"];
self.noteID=[[[NSArray alloc]initWithArray:_fetchedObjects]valueForKey:#"moodleCode"];
self.classTitleLable.text=self.moodleName;
self.title=self.moodleName;
[self.allNotes reloadData];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section{
return 0;
}
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
// This will create a "invisible" footer
return 0.01f;
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return [self.fetchedObjects count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString * cellIdnt =#"noteCell";
AllClassNotesCell *cell =(AllClassNotesCell *) [tableView dequeueReusableCellWithIdentifier:cellIdnt forIndexPath:indexPath];
// Configure the cell...
// Get current date & time
NSDate *currDate = [self.insertDates objectAtIndex:indexPath.row];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:#"dd/MM/YY HH:mm"];
NSString* dateToString =[dateFormatter stringFromDate:currDate];
cell.textLabel.text= [self.noteTitle objectAtIndex:indexPath.row] ;
cell.detailTextLabel.text=dateToString;
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 78;
}
-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath{
id delegate =[[UIApplication sharedApplication]delegate];
// Delete the role object that was swiped
NSUInteger currentSelect = indexPath.row;
NSManagedObjectContext *context = [delegate managedObjectContext];
Notes * roleToDelete= [self.fetchedObjects objectAtIndex:currentSelect];
[context deleteObject:roleToDelete];
// Save the context.
NSError *error;
if (![context save:&error])
{
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
}
[_fetchedObjects removeObjectAtIndex:currentSelect];
[self.allNotes reloadData];
}
-(void)viewWillAppear:(BOOL)animated{
id delegate =[[UIApplication sharedApplication]delegate];
NSError*error=nil;
NSManagedObjectContext *context = [delegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Notes"
inManagedObjectContext:context];
NSPredicate * predicate =[NSPredicate predicateWithFormat:[NSString stringWithFormat:#"moodleCode=='%#'",self.moodeleID]];
[fetchRequest setPredicate:predicate];
[fetchRequest setEntity:entity];
self.fetchedObjects = (NSMutableArray *)[context executeFetchRequest:fetchRequest error:&error];
self.noteTitle =[[[NSArray alloc]initWithArray:_fetchedObjects]valueForKey:#"title"];
self.insertDates =[[[NSArray alloc]initWithArray:_fetchedObjects]valueForKey:#"insertDate"];
self.classTitleLable.text=self.moodleName;
self.title=self.moodleName;
[self.allNotes reloadData];
}
#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 {
if ([[segue identifier]isEqual:#"newNote"]) {
NewClassNote * newNoteView =[segue destinationViewController];
newNoteView.moodleID =self.moodeleID;
newNoteView.newOrOld =YES;
}else if ([[segue identifier]isEqual:#"showNote"])
{
NewClassNote * dvc =[segue destinationViewController];
NSUInteger currentSelect = [self.allNotes indexPathForSelectedRow].row;
NSLog(#"Send is %lu",(unsigned long)currentSelect);
dvc.returnData =[self.fetchedObjects objectAtIndex:currentSelect];
NewClassNote *destViewController = segue.destinationViewController;
destViewController.comingData = [self.noteTitle objectAtIndex:[[self.allNotes indexPathForSelectedRow] row]];
destViewController.insertDate= [self.insertDates objectAtIndex:[[self.allNotes indexPathForSelectedRow] row]];
[self.allNotes reloadData];
}
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
#end
Can you explain to me why I get this error? The total rows after deletion is different than before deletion but I don't know why this errors?

Answer 1

You error goes from here:
self.fetchedObjects = (NSMutableArray *)[context executeFetchRequest:fetchRequest error:&error];
-executeFetchRequest:error: returns NSArray, it's immutable, if you just cast it to NSMutableArray it won't magically change itself. But later you try to
[_fetchedObjects removeObjectAtIndex:currentSelect];
which is sending -removeObjectAtIndex to an NSArray instance.
You can try to solve it like this:
self.fetchedObjects = [[context executeFetchRequest:fetchRequest error:&error] mutableCopy];