Error: '-[__NSCFArray removeObjectAtIndex:]: mutating method sent to immutable object' - ios

Question

I'm attempting to allow my user to be able to delete/remove a row from a tableView (remove an object from an existing NSMutableArray), however when I try and delete the row, I get the following crash error:
Terminating app due to uncaught exception
'NSInternalInconsistencyException', reason: '-[__NSCFArray
removeObjectAtIndex:]: mutating method sent to immutable object'
Does anyone know why this might be? See code below. Apologies for the lengthy code.
.h
#property (strong, nonatomic) NSMutableArray *descripData;
.m
- (void)viewDidLoad {
[super viewDidLoad];
self.descripData = [[NSMutableArray alloc] init];
refreshControl = [[UIRefreshControl alloc]init];
[self.tableView addSubview:refreshControl];
[refreshControl addTarget:self action:#selector(refreshTable) forControlEvents:UIControlEventValueChanged];
NSMutableDictionary *viewParams = [NSMutableDictionary new];
[viewParams setValue:#"storeditems" forKey:#"view_name"];
[DIOSView viewGet:viewParams success:^(AFHTTPRequestOperation *operation, id responseObject) {
self.descripData = responseObject;
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Failure: %#", [error localizedDescription]);
}];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if ([self.storageData count] > 0 && self.descripData.count > 0)
{
return [self.descripData count];
}
else
return 0;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *DoctorsTableIdentifier = #"StorageItemTableViewCell";
StorageItemTableViewCell *cell = (StorageItemTableViewCell *)[tableView dequeueReusableCellWithIdentifier:DoctorsTableIdentifier];
if (cell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"StorageItemTableViewCell" owner:self options:nil];
cell = [nib objectAtIndex:0];
}
if (self.storageData.count > 0 && self.descripData.count > 0) {
noitemsView.hidden = YES;
NSDictionary *title = [self.descripData objectAtIndex:indexPath.row];
[[cell itemName] setText:[title objectForKey:#"node_title"]];
NSDictionary *node = [self.descripData objectAtIndex:indexPath.row];
[[cell itemDescrip] setText:[node objectForKey:#"body"]];
NSDictionary *value = [self.descripData objectAtIndex:indexPath.row];
[[cell valueLabel] setText:[value objectForKey:#"dollarvalue"]];
NSLog(#"%#", self.descripData);
NSDictionary *quantity = [self.descripData objectAtIndex:indexPath.row];
[[cell quantityLabel] setText:[quantity objectForKey:#"quantity"]];
NSLog(#"%#", self.descripData);
NSString *secondLink = [[self.descripData objectAtIndex:indexPath.row] objectForKey:#"photo"];
[cell.itemPhoto sd_setImageWithURL:[NSURL URLWithString:secondLink]];
}
else {
noitemsView.hidden = NO;
}
return cell;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 152;
}
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source
[self.descripData removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView reloadData];
}
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
ItemDetailViewController *detailViewController = [[ItemDetailViewController alloc] initWithNibName:#"ItemDetailViewController" bundle:nil];
detailViewController.itemDetail = [[values objectAtIndex:indexPath.row] objectForKey:#"node_title"];
detailViewController.itemDetail = [self.descripData objectAtIndex:indexPath.row];
detailViewController.secondLink = self.descripData[indexPath.row][#"photo"];
[self.navigationController pushViewController:detailViewController animated:YES];
}

Answer 1

Check the line self.descripData = responseObject;. It looks like you are probably setting your descripData property to point to a NSArray, not an NSMutableArray. If you really need the mutability, try self.descripData = [responseObject mutableCopy]; instead.

Answer 2

I suspect that the following assignment causes the problem:
self.descripData = responseObject;
The response object itself is immutable, assigning it to a NSMutableArray does not change that fact, you need to create a NSMutableArray with the contents of the responseObject:
self.descripData = [NSMutableArray arrayWithArray:responseObject];

Answer 3

Most likely happening on the following line:
self.descripData = responseObject;
You're replacing your previous mutable array for descripData with a new one, which apparently is not mutable. You can either create a new mutable array from this new array using [NSMutableArray arrayWithArray:responseObject], or you can add the contents of responseObject to your current mutable array.
It's important to pay attention when you assign something of type id to a variable, because there's no compile-time type checking that can occur. This sometimes results in errors at runtime.

Answer 4

Face this issue because NSUserDefaults always returns an immutable object.
Please while retrieving Mutable object from NSUserDefaults please refer below code.
NSMutableArray *storeArray = [[defaultDefects objectForKey:#"defaultStoreDefects"]mutableCopy];