Objective-C - UICollectionView with wrong indexpaths - objective-c

Question

I have a UICollectionView that I'm trying to use as a matrix with a first "column" used as the name of the row (colors) and then in the other items I put how many goods I'm buying. I had to split it in two collections because the header has to be fixed in that position.
My problem is that the initial situation is this:
Then, when I scroll the gray collection a bit and play with it...
The code which should manage the part is this:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
CGSize cellSize = cell.frame.size;
int item = (int)indexPath.item;
int section = (int)indexPath.section;
NSLog(#"S:%d I:%d",section,item);
/*NSMutableArray *array = [matrice objectAtIndex:section];
if([array objectAtIndex:row] != [NSNull null]){
cell = [[matrice objectAtIndex:section] objectAtIndex:10-row];
return cell;
}else{
[[matrice objectAtIndex:section] replaceObjectAtIndex:row withObject:cell];
}*/
if(item == 0){ //Colori
int labelWidth = cellSize.width - 5;
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake((cellSize.width/2)-labelWidth/2, (cellSize.height/2)-labelWidth/2, labelWidth, labelWidth)];
Colore *colore = [cartellaColore.arrayColori objectAtIndex:section];
[label setText:colore.descrizione];
[label setTextAlignment:NSTextAlignmentCenter];
[label setFont:[UIFont fontWithName:#"HelveticaNeue-Bold" size:14]];
[cell addSubview:label];
[cell setBackgroundColor:[UIColor whiteColor]];
}
else{
[cell setBackgroundColor:[UIColor grayColor]];
}
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(2*section, 2*item, 35, 10)];
[label setText:[NSString stringWithFormat:#"S:%d I:%d",section,item]];
[label setTextAlignment:NSTextAlignmentCenter];
[label setFont:[UIFont fontWithName:#"HelveticaNeue-Bold" size:8]];
[cell addSubview:label];
return cell;
}
What am I doing wrong?
EDIT:
I let the program write different label on the same cell just for showing that the indexpaths are wrong. If they were correct it would just re-add the label in the same position with the same text (which I know is still wrong but it was just for debugging)

Answer 1

You can't add a label like that in your cellForRowAtIndexPath, you have to subclass a UICollectionViewCell.
I made a response to this kind of issue here : UICollectionView adding image to a cell
Just apply what I explained to a UILabel instead of a UIImageView, and your issues should disappear.
Let me know though.

Answer 2

This is your mistake:
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(2*section, 2*item, 35, 10)];
[label setText:[NSString stringWithFormat:#"S:%d I:%d",section,item]];
[label setTextAlignment:NSTextAlignmentCenter];
[label setFont:[UIFont fontWithName:#"HelveticaNeue-Bold" size:8]];
**[cell addSubview:label];**
you are stacking labels in cells, the cell are reusable, and each time you dequeue a reusable cell you add a label to it so if the dequeued cell has already been presented you will add another label to it and ect. You should protect your self from that by checking if that cell already has label and if it has than just change its text property, and if it doesn't do the code above... One way to do it is to add a specific tag to the label and then when you dequeue a cell just check if it has a view with that tag, if it has cast the view to label and change its text property so:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
if([cell viewWithTag:111]){
UILabel *label = (UILabe*)[cell viewWithTag:111];
[label setText:[NSString stringWithFormat:#"S:%d I:%d",section,item]];
}
else{
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(2*section, 2*item, 35, 10)];
[label setText:[NSString stringWithFormat:#"S:%d I:%d",section,item]];
[label setTextAlignment:NSTextAlignmentCenter];
[label setFont:[UIFont fontWithName:#"HelveticaNeue-Bold" size:8]];
[label setTag:111];
[cell addSubview:label];
}
...