1.长按cell的情况下实现拖动，所以理应想到用长按手势。

2.既然实现移动cell，就要看看UICollectionView 有没有方法或者协议可以移动的。通过查看UICollectionView的协议方法，可以在UICollectionViewDataSource中看到有两个方法。

- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath;

• (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath;

3.OK 知道了以上两个步骤，那么就可以开始写代码了。

// 设置手势

• (void)setupGesture
  {
  UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handlelongGesture:)];

  [self.collectionView addGestureRecognizer:longPress];
  }

• (void)handlelongGesture:(UILongPressGestureRecognizer *)longGesture {
  //判断手势状态
  switch (longGesture.state) {
  case UIGestureRecognizerStateBegan:
  　　　　{
  //判断手势落点位置是否在路径上
  NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:[longGesture locationInView:self.collectionView]];
  if (indexPath == nil) {
  break;
  }
  //在路径上则开始移动该路径上的cell
  [self.collectionView beginInteractiveMovementForItemAtIndexPath:indexPath];
  }
  break;
  case UIGestureRecognizerStateChanged:
  //移动过程当中随时更新cell位置
  [self.collectionView updateInteractiveMovementTargetPosition:[longGesture locationInView:self.collectionView]];
  break;
  case UIGestureRecognizerStateEnded:
  //移动结束后关闭cell移动
  [self.collectionView endInteractiveMovement];
  break;
  default:
  [self.collectionView cancelInteractiveMovement];
  break;
  }
  }

• (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath{
  //返回YES允许其item移动
  return YES;
  }

• (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath {
  //取出源item数据
  id objc = [_dataSource objectAtIndex:sourceIndexPath.item];
  //从资源数组中移除该数据
  [_dataSource removeObject:objc];
  //将数据插入到资源数组中的目标位置上
  [_dataSource insertObject:objc atIndex:destinationIndexPath.item];
  }

注：_dataSource 是你的数据源。