UICollectionView实现cell拖动效果

1.在UICollectionView的视图上添加长按手势

UILongPressGestureRecognizer *longGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handlelongGesture:)];
    [self.collectionView addGestureRecognizer:longGesture];
    

2.在点击的时候，获取到当前点击的cell的indexpath，并在不同的手势状态下，进行一些判断或者添加一些约束条件【因为我的情景是cell中显示不同的服务，而最后一个cell与其他不同，不参与排序，所以我需要保证拖动的cell不可以到最后一个位置，并且最后一个cell不可以拖动】

- (void)handlelongGesture:(UILongPressGestureRecognizer *)longGesture {
    NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:[longGesture locationInView:self.collectionView]];
    UICollectionViewCell *tmpCell = [self.collectionView cellForItemAtIndexPath:indexPath];
    [tmpCell.layer shake];
    //判断手势状态
    switch (longGesture.state) {
        case UIGestureRecognizerStateBegan:{
            [tmpCell.layer playSystemShake];
            //判断手势落点位置是否在路径上
            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:
            NSLog(@"%lu",(unsigned long)_showDataArr.count);
            //判断是否落在最后的加号上
            if (indexPath.row == _showDataArr.count) {
                break;
            }
            //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;
    }
}

3我们还需要实现UIcollectionView的一个代理方法，并保证不参与拖动的cell不可移动

- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath{
    //返回YES允许其item移动
    if(indexPath.row != [_showDataArr count]) {
        return YES;
    }
    return NO;
}

4实现数据的重新排序

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