UICollectionView space between cells

Question

In my case I want completely remove any spaces between UICollectionViewCell's. In iPhone 5 it works correct but iPhone 6 and up. Every time I scroll or in the initial load UICollectionView adds empty space for different rows. I know that could be difference in float values. For example 8.88888881 and 8.88888881.

Green Line is empty space (collection view background color)

Every time I scroll this line change position.

My code:

- (CGSize)collectionView:(UICollectionView *)collectionView
                  layout:(UICollectionViewLayout *)collectionViewLayout
  sizeForItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
    CGFloat widthAndHeight = [self widthAndHeightForActiveCollectionViewItem];
    if (widthAndHeight < 22) {
        widthAndHeight = 22;
    }
    CGFloat result = lroundf(widthAndHeight * self.venueLayoutZoom);
    return CGSizeMake(result, result);
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
{
    return 0;
}

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    return UIEdgeInsetsZero;
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
{
    return 0;
}

For UICollectionViewFlowLayout I use this because I need to scroll in both directions. Every time size is correct and without any float values. I always tried to modify UICollectionView width. For example: I have 29 elements in one row and I want it to be 11 px width each. Then I set up width to 319.

And the second question is: I want to create cell with only right bottom rounded corner like . But again iPhone 6 and up shows me wrong result such as . (look at this line on top). I want just a smooth colors. But when I scroll left/right it could be normal.

UICollectionViewCell code:

- (void)prepareForReuse
{
    [self.circularLayer removeFromSuperlayer];
}

- (void)awakeFromNib
{
    [super awakeFromNib];
    [self allocAndAddLayers];
}

- (void)allocAndAddLayers
{
    self.circularLayer = [CALayer layer];
    [self.layer addSublayer:self.circularLayer];
}

- (void)layoutSubviews
{
    [self updateRoundedCorners];
}

- (void)updateRoundedCorners
{
   self.circularLayer.bounds = bounds;
        self.circularLayer.position = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds));
            CGRect rect = self.circularLayer.bounds;
            CGFloat radius = CGRectGetWidth(rect) / kVenueLayoutCellDefaultCornerRadiusDivider;
            UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corners cornerRadii:CGSizeMake(radius, radius)];
            CAShapeLayer *maskLayer = [CAShapeLayer layer];
            maskLayer.frame = bounds;
            maskLayer.path = maskPath.CGPath;
            self.circularLayer.mask = maskLayer;
}