间距的简单代码

let layout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
layout.minimumInteritemSpacing = 10 // Some float value

试试这个方法:

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView
                    layout:(UICollectionViewLayout*)collectionViewLayout
    insetForSectionAtIndex:(NSInteger)section {

    UIEdgeInsets insets = UIEdgeInsetsMake(?, ?, ?, ?);

    return insets;
}

回答Swift 3.0, Xcode 8

1.确保你设置了集合视图委托

class DashboardViewController: UIViewController {
    @IBOutlet weak var dashboardCollectionView: UICollectionView!

    override func viewDidLoad() {
        super.viewDidLoad()
        dashboardCollectionView.delegate = self
    }
}

2.实现uicollectionviewdelegatflowlayout协议，而不是UICollectionViewDelegate。

extension DashboardViewController: UICollectionViewDelegateFlowLayout {
    fileprivate var sectionInsets: UIEdgeInsets {
        return .zero
    }

    fileprivate var itemsPerRow: CGFloat {
        return 2
    }

    fileprivate var interitemSpace: CGFloat {
        return 5.0
    }

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        let sectionPadding = sectionInsets.left * (itemsPerRow + 1)
        let interitemPadding = max(0.0, itemsPerRow - 1) * interitemSpace
        let availableWidth = collectionView.bounds.width - sectionPadding - interitemPadding
        let widthPerItem = availableWidth / itemsPerRow

        return CGSize(width: widthPerItem, height: widthPerItem)
    }

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        insetForSectionAt section: Int) -> UIEdgeInsets {
        return sectionInsets
    }

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0.0
    }

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

使用水平流布局，我也得到了10点之间的单元格间距。为了移除间距，我需要将minimumlinespespaces和minimumInterItemSpacing设置为零。

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

此外，如果所有单元格大小相同，直接在流布局上设置属性比使用委托方法更简单、更有效。

上面vojtech-vrbka的解决方案是正确的，但它会触发一个警告:

警告:UICollectionViewFlowLayout缓存的帧不匹配索引路径-缓存值:这可能是因为流布局子类layout是修改UICollectionViewFlowLayout返回的属性而没有复制它们

下面的代码应该修复它:

class CustomViewFlowLayout : UICollectionViewFlowLayout {

   let cellSpacing:CGFloat = 4

   override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
       let original = super.layoutAttributesForElementsInRect(rect)

       if let original = original {
           let attributes = NSArray.init(array: original, copyItems: true) as! [UICollectionViewLayoutAttributes]

           for (index, attribute) in attributes.enumerate() {
                if index == 0 { continue }
                let prevLayoutAttributes = attributes[index - 1]
                let origin = CGRectGetMaxX(prevLayoutAttributes.frame)
                if(origin + cellSpacing + attribute.frame.size.width < self.collectionViewContentSize().width) {
                    attribute.frame.origin.x = origin + cellSpacing
                }
            }
            return attributes
       }
       return nil
   }
}

记住，它是最小行间距，而不是最小项间距或单元格间距。因为你的collectionView的滚动方向是水平的。

如果是垂直的，则需要为单元格之间的水平空间设置单元格空间或项间空间，为单元格之间的垂直空间设置行间距。

objective - c版本

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

斯威夫特版本:

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