NSInternalInconsistencyException while deleting cell from collectionView - ios

Question

I want to delete a cell from a UICollectionView. While deleting cell I get
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of items in section 0. The number of items contained in an existing section after the update (5) must be equal to the number of items contained in that section before the update (5), plus or minus the number of items inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of items moved into or out of that section (0 moved in, 0 moved out).' Error.
Here is my code:
[self.imgArray removeObjectAtIndex:indexForDelete];
[self.collectionView performBatchUpdates:^{
NSIndexPath *indexPath =[NSIndexPath indexPathForItem:indexForDelete inSection:0];
[self.collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
} completion:^(BOOL finished) {
}];
I am appending one dummy cell when my array count is not 5
Here is code for numberOfItems in numberOfItemsInSection
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
if(self.imgArray.count == 5)
{
return self.imgArray.count ;
}
else
{
return self.imgArray.count + 1;
}
}
I found many solution on Google and Stackoverflow but nothing found help full for me.

Answer 1

performBatchUpdates mainly used to perform actions for multiple cells. i.e. delete, insert, move.
Try this,
[self.collectionObj performBatchUpdates:^{
[self.imgArray removeObjectAtIndex:indexForDelete];
NSIndexPath *indexPath =[NSIndexPath indexPathForItem:indexForDelete inSection:0];
[self.collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
[self.collectionView reloadData];
} completion:^(BOOL finished) {
}];
You can also try directly for 1 cell delete without using performBatchUpdates
[self.imgArray removeObjectAtIndex:indexForDelete];
NSIndexPath *indexPath =[NSIndexPath indexPathForItem:indexForDelete inSection:0];
[self.collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
[self.collectionView reloadData];
Hope, this will help you.
Thanks

Answer 2

I think you may need to separate the update into two stages to avoid the NSInternalInconsistencyException.
#property (assign, nonatomic) BOOL isMyCollectionViewUpdating;
//...
[self.imgArray removeObjectAtIndex:indexForDelete];
[self.collectionView performBatchUpdates:^{
self.isMyCollectionViewUpdating = YES;
NSIndexPath *indexPath =[NSIndexPath indexPathForItem:indexForDelete inSection:0];
[self.collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
} completion:^(BOOL finished) {
self.isMyCollectionViewUpdating = NO;
[self.collectionView reloadData];
}];
and for the collection view numberOfItemInSection
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
if (self.isMyCollectionViewUpdating)
{
return self.imgArray.count;
} else {
if(self.imgArray.count == 5)
{
return self.imgArray.count ;
}
else
{
return self.imgArray.count + 1;
}
}
}