swift UICollectionView Item重新排序

我们一般情况下,自定义的collectionview item排序出来的效果是这样的!

一般情况下实现效果

这样就会出现不够一屏时,最上面一行无法补齐,或者最重要的,你的产品经理觉得你和安卓的显示有差别!

所以就有重新排序,拿到所有的item 并重新

那么,就要重写UICollectionViewFlowLayout的类

写一个类集成于UICollectionViewFlowLayout

func targetPositionWithItem(item: Int, resultX x: inout Int?, resultY y: inout Int?) {
       let page = item / (self.itemCountPerRow * self.rowCount)
       let theX = item % self.itemCountPerRow + page * self.itemCountPerRow
      let theY = item / self.itemCountPerRow - page * self.rowCount
      if x != nil {
          x = theX
      }
      if y != nil {
          y = theY
      }
  }

.

   func originItemAtX(x: Int, y: Int) -> Int {
    let item = x * self.rowCount + y
    return item
}

实现效果 效果

项目还做了关于collectionView整屏滑动的实现,
就是对所拿到的模型进行整数填充

 // 这是关于如何让 item 整屏滑动对模型的操作 就是让数组补齐一屏 把空的UI隐藏并对didSelect方法进行判断
// 这里有第一屏不满少于5个对整个collectionview的高度进行改变

    var activityModel = [lawActivityinfo]() {
    didSet {
        pageControl.numberOfPages = self.activityModel.count / 8 + 1
        if activityModel.count < 5 {
            self.mineLayout.rowCount = 1
            let fix4 = activityModel.count % 4
            let num4 = Int(4 - fix4)
            if fix4 > 0 {
                for _ in 1...num4 {
                    let model = lawActivityinfo()
                    activityModel.append(model)
                }
            }
            self.collectionView.snp.updateConstraints({ (make) in
                make.height.equalTo(Screen.autoScaleH(h: 120))
            })
            pageControl.frame = CGRect(x: 0, y: Screen.autoScaleH(h: 120) + 3, width: Screen.width, height: 10)
        } else {
            self.mineLayout.rowCount = 2
            let fix = activityModel.count % 8
            let fixNum = Int(8 - fix)
            if fix > 0 {
                for _ in 1...fixNum {
                    let model = lawActivityinfo()
                    activityModel.append(model)
                }
            }
            self.collectionView.snp.updateConstraints({ (make) in

                make.height.equalTo(Screen.autoScaleH(h: 230))
            })
            pageControl.frame = CGRect(x: 0, y: Screen.autoScaleH(h: 230) + 3, width: Screen.width, height: 10)

        }
        dog(activityModel.count)

        collectionView.reloadData()
    }
}

如果还有更好的实现方法请多多指教~~~

github: https://github.com/SummerOO/myCollectionView