iOS CollectionView 'NSInternalInconsistencyException' - ios

Question

So, I'm playing around with iOS programming a little bit. Don't got a lot of time, but I've been postponing to learn it for too long now. But I got stuck for 2 days now with this freaking problem. I'm getting the following error when I try to add cells to my collectionView.
'NSInternalInconsistencyException', reason: 'attempt to insert item 0 into section 0, but there are only 0 items in section 0 after the update'
Here's my code:
#interface DocumentsViewController() {
FileManager *fileManager;
NSMutableArray *folderContent;
}
#end
#implementation DocumentsViewController
#synthesize fileList;
- (void)viewDidLoad
{
[super viewDidLoad];
folderContent = [[NSMutableArray alloc] init];
fileManager = [[FileManager alloc] init];
NSArray *items = [fileManager getDirectoryInfo];
[self createFileList:items];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)createFileList:(NSArray *)items
{
for(NSString *item in items)
{
NSInteger count = [folderContent count];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:count inSection:0];
[folderContent insertObject:item atIndex:count];
[self.fileList insertItemsAtIndexPaths:#[indexPath]];
}
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
FilesViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"DefaultCell" forIndexPath:indexPath];
cell.image.image = [UIImage imageNamed:#"folder.png"];
cell.label.text = #"oi"; //objects[indexPath.row];
return cell;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return folderContent.count;
}
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 1;
}
#end
Thanks in advance,
Lucas
UPDATE
Ok, so after a few VERY helpful tips, I got another error message:
'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of items in section 0. The number of items contained in an existing section after the update (1) must be equal to the number of items contained in that section before the update (1), plus or minus the number of items inserted or deleted from that section (1 inserted, 0 deleted) and plus or minus the number of items moved into or out of that section (0 moved in, 0 moved out).'
Like I said below, I might be using (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section wrong cause it's been called twice in a row, without giving time for the value of folderContent.count to change.

Answer 1

Do you really want to use insertItemsAtIndexPath when you create your list? This will cause them to animate in one at a time. Why not do a [self.fileList reloadData] after it is completely populated after the for loop?
In addition I think this line may be giving you issues -
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:count inSection:0];
You are using a collection view which doesn't have rows in the same sense as UITableViews (note the indexPathForItem instead of indexPathForRow)
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:count inSection:0];