Uicollectionview chess style grid - ios

Question

I have to implement a chess style grid view to show some radial progress bar.!
I made the grid using some inefficient algorithm to do this, since UiCollectionView don't use rows and columns, and it worked, but when the user scrolled the collection to the limit and the "row" of the collection disappear from the screen and the user release the screen and the UICollectionViewCells reappear they switched its colors.
I know the switching happens by the BOOLs, but i don't know how solve this.
This is my algorithm (i have 2 differents UICollectionViewCells, one for each color)
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *identifier = #"Cell";
static NSString *identifierPair = #"CellPair";
UICollectionViewCell *cell ;
UILabel *title;
//...Creating the circle progress bar....
if ((indexPath.item % 2) == 0) {
if (isPair) {
cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifierPair forIndexPath:indexPath];
isPair = NO;
title = (UILabel *)[cell viewWithTag:12];
}
else
{
cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
isPair = YES;
title = (UILabel *)[cell viewWithTag:11];
}
}
else {
if (isUneven) {
cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifierPair forIndexPath:indexPath];
isUneven = NO;
title = (UILabel *)[cell viewWithTag:12];
}
else
{
cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
isUneven = YES;
title = (UILabel *)[cell viewWithTag:11];
}
}
//...Setting the name to the cell....
return cell;
}

Answer 1

This seems more the case of using a single checkered background inside the UICollectionView, but since I'm not sure that it is doable you could do something like:
+ (BOOL)checkersCellAtIndexIsDark:(NSIndexPath *)indexPath {
NSInteger squareIndex = indexPath.item % 4;
return (squareIndex == 0 || squareIndex == 3);
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"Cell" forIndexPath:indexPath];
cell.backgroundColor = ([[self class] checkersCellAtIndexIsDark:indexPath])? [UIColor orangeColor] : [UIColor yellowColor];
// Set other things
return cell;
}
I don't understand why you use different reuseIdentifiers and titleLabels for different backgrounds since I don't notice from the screens, but you can always edit this code

Answer 2

You didn't have to use 2 different cells to change the background.
All you need is to set the default color of the background and when the indexPath.item is even, just set the other color for the cell background.
But is important to set the default color first, otherwise you will have the same result.