iOS - UICollectionView spacing still there when set to 0 - How to set with no spacing between cells

Simple solution for your Query. Add this in your viewController's .m file:

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    ProductDetailViewController *HomeVC = [self.storyboard instantiateViewControllerWithIdentifier:@"ProductDetailView"];    HomeVC.title = @"DemoProject";    [self.navigationController pushViewController:HomeVC animated:YES];}- (UIEdgeInsets)collectionView:(UICollectionView*)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {    return UIEdgeInsetsMake(0, 0, 0, 0); // top, left, bottom, right}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {    return 0.0;}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {    return 0.0;}

Swift 3 version of @MihirOza 's solution

Worked for both Horizontal and Vertical collection views

Code

// removing spacingfunc collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {    return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)}func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {    return 0.0}func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {    return 0.0}

You have to create custom UICollectionViewLayout.

Space between the cells will be equal to cellSpacing.

final class CustomFlowLayout: UICollectionViewFlowLayout {    let cellSpacing: CGFloat = 0    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {        if let attributes = super.layoutAttributesForElements(in: rect) {            for (index, attribute) in attributes.enumerated() {                if index == 0 { continue }                let prevLayoutAttributes = attributes[index - 1]                let origin = prevLayoutAttributes.frame.maxX                if (origin + cellSpacing + attribute.frame.size.width < self.collectionViewContentSize.width) {                    attribute.frame.origin.x = origin + cellSpacing                }            }            return attributes        }        return nil    }}