Cell spacing in UICollectionView

Using a horizontal flow layout, I was also getting a 10 points spacing between cells. To remove the spacing I needed to set minimumLineSpacing as well as minimumInterItemSpacing to zero.

UICollectionViewFlowLayout *flow = [[UICollectionViewFlowLayout alloc] init];
flow.itemSize = CGSizeMake(cellWidth, cellHeight);
flow.scrollDirection = UICollectionViewScrollDirectionHorizontal;
flow.minimumInteritemSpacing = 0;
flow.minimumLineSpacing = 0;

Also, if all your cells are the same size, it's simpler and more efficient to set the property on the flow layout directly instead of using delegate methods.

Supporting the initial question. I tried to get the spacing to 5px on the UICollectionView but this does not work, as well with a UIEdgeInsetsMake(0,0,0,0)...

On a UITableView I can do this by directly specifying the x,y coordinates in a row...

Heres my UICollectionView code:

#pragma mark collection view cell layout / size
- (CGSize)collectionView:(UICollectionView*)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    return [self getCellSize:indexPath];  // will be w120xh100 or w190x100
    // if the width is higher, only one image will be shown in a line
}

#pragma mark collection view cell paddings
- (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 5.0;
}

Update: Solved my problem, with the following code.

ViewController.m

#import "ViewController.h"
#import "MagazineCell.h" // created just the default class. 

static NSString * const cellID = @"cellID";

@interface ViewController ()

@end

@implementation ViewController

#pragma mark - Collection view
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 30;
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    MagazineCell *mCell = (MagazineCell *)[collectionView dequeueReusableCellWithReuseIdentifier:cellID forIndexPath:indexPath];

    mCell.backgroundColor = [UIColor lightGrayColor];

    return mCell;
}

#pragma mark Collection view layout things
// Layout: Set cell size
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

    NSLog(@"SETTING SIZE FOR ITEM AT INDEX %d", indexPath.row);
    CGSize mElementSize = CGSizeMake(104, 104);
    return mElementSize;
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
    return 2.0;
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
    return 2.0;
}

// Layout: Set Edges
- (UIEdgeInsets)collectionView:
(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
   // return UIEdgeInsetsMake(0,8,0,8);  // top, left, bottom, right
    return UIEdgeInsetsMake(0,0,0,0);  // top, left, bottom, right
}

@end

Remember, it is minimum line space, not minimum inter item spacing or cell space. Because your collectionView's scroll direction is HORIZONTAL.

If it is vertical then you need to set cell space or inter item space for horizontal space between cells and line spacing for vertical space between cells.

Objective-C version

- (CGFloat)collectionView:(UICollectionView *)collectionView
                       layout:(UICollectionViewLayout*)collectionViewLayout
    minimumLineSpacingForSectionAtIndex:(NSInteger)section
    {
        return 20;
    }

Swift version:

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 20
}

I know that the topic is old, but in case anyone still needs correct answer here what you need:

1. Override standard flow layout.

2. Add implementation like that:

   - (NSArray *) layoutAttributesForElementsInRect:(CGRect)rect {
       NSArray *answer = [super layoutAttributesForElementsInRect:rect];
   
       for(int i = 1; i < [answer count]; ++i) {
           UICollectionViewLayoutAttributes *currentLayoutAttributes = answer[i];
           UICollectionViewLayoutAttributes *prevLayoutAttributes = answer[i - 1];
           NSInteger maximumSpacing = 4;
           NSInteger origin = CGRectGetMaxX(prevLayoutAttributes.frame);
   
           if(origin + maximumSpacing + currentLayoutAttributes.frame.size.width < self.collectionViewContentSize.width) {
               CGRect frame = currentLayoutAttributes.frame;
               frame.origin.x = origin + maximumSpacing;
               currentLayoutAttributes.frame = frame;
           }
       }
       return answer;
   }
   

where maximumSpacing could be set to any value you prefer. This trick guarantees that the space between cells would be EXACTLY equal to maximumSpacing!!