这解决了我的问题。

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
    {
        return CGSizeMake((UIScreen.mainScreen().bounds.width-15)/2,208); //use height whatever you wants.
    }

我认为您应该使用自动布局，使您的单元格宽度为CollectionView宽度的一半，并减去一些点，但我不确定这是否可以在故事板中设置，我主要在代码中进行设置，使用“collectionViewFlowLayout.setItemSize”设置相对于屏幕宽度的项目大小，或者UICollectionViewDelegateFlowLayout也可以;

这样做：

func collectionView(collectionView: UICollectionView,
        layout collectionViewLayout: UICollectionViewLayout,
        sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
    {
           collectionData.contentInset=UIEdgeInsetsMake(0,0,0,0)
        let screensize:CGRect=UIScreen.mainScreen().bounds
        let width=screensize.width

        if (width==320)
        {
            let size:CGSize=CGSizeMake(129,140)
            collectionData.contentInset=UIEdgeInsetsMake(0,10,0,10)
            return size
        }
        else if(width==375)
        {
            let size:CGSize=CGSizeMake(166,181)
            collectionData.contentInset=UIEdgeInsetsMake(0,0,0,0)
            return size
        }
        else if(width==414)
        {
            if(UIDevice.currentDevice().orientation .isLandscape)
            {
                let size:CGSize=CGSizeMake(300,185)
                collectionData.contentInset=UIEdgeInsetsMake(0,0,0,0)
                print("com,ing inside orientatiom");
                return size

            }
            let size:CGSize=CGSizeMake(177,185)
            collectionData.contentInset=UIEdgeInsetsMake(0,0,0,0)
            return size
        }
        let size:CGSize=CGSizeMake(358,292)
        return size

    }

你可以为所有设备调整公共空间-目标C版本

- (CGSize)collectionView:(UICollectionView *)collectionView 
              layout:(UICollectionViewLayout *)collectionViewLayout 
   sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

   CGFloat height = self.view.frame.size.height;
   CGFloat width  = self.view.frame.size.width;
   // in case you you want the cell to be 40% of your controllers view
   return CGSizeMake(width*0.4,height*0.4)
 }