通过长按手势交换UICollectionViewCells位置

Question

我一直在努力解决我在这里做错了什么。我的目标是能够拖动CollectionViewCell并让它用拖动的单元替换目标单元格，同时让替换的单元格接管最初拖动的单元格上的位置。这甚至让我感到困惑！我可以得到拖动和细胞替换，但我的问题是，当我发生时，我会在集合中留下越来越多的空单元格。

我对目标C来说相当新，所以很可能我在这里错过了一些愚蠢的东西..任何帮助都会非常感激。希望我已经包含足够的相关代码来帮助和链接图像以显示我的问题...

Cheers Leigh

Collection View Issue Image

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self getPlayerPositions];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)getPlayerPositions
{
    SQL_PlayerTracker *pt = [[SQL_PlayerTracker alloc]init];
    playerPositionsARR = [[pt getPositions:MD]mutableCopy];
    [CV_playerPositions reloadData];
}

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return [playerPositionsARR count];
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    OBJ_Positions *s = [playerPositionsARR objectAtIndex:indexPath.row];

    CVC_PlayerPositions *pcell = (CVC_PlayerPositions *)[collectionView dequeueReusableCellWithReuseIdentifier:@"PositionCell" forIndexPath:indexPath];
    pcell.playerName.text = s.playerName;
    pcell.positionName.text = s.position;
    pcell.playerNumber.text = [NSString stringWithFormat:@"%@",s.playerNumber];

    if (pcell.selected) {
        pcell.backgroundColor = [UIColor greenColor];
    }

    return pcell;
}

- (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath
{
    NSLog(@"MOVED INDEX %i TO %i",indexPath.row,newIndexPath.row);
    OBJ_Positions *oldPlayer = [playerPositionsARR objectAtIndex:newIndexPath.row];
    OBJ_Positions *newPlayer = [playerPositionsARR objectAtIndex:indexPath.row];

    //REMOVE TARGET POSITION FROM ARRAY
    [playerPositionsARR removeObjectAtIndex:newIndexPath.row];
    //INSERT NEW PLAYER POSITION IN TARGET POSITION
    [playerPositionsARR insertObject:newPlayer atIndex:newIndexPath.row];
    //INSERT OLD PLAYER IN MOVED PLAYERS POSITION
    [playerPositionsARR insertObject:oldPlayer atIndex:indexPath.row];
    //REMOVE ADDED POSITION OBJECT FROM INSERTION
    [playerPositionsARR removeObjectAtIndex:indexPath.row +1];
    [CV_playerPositions reloadData];
}

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    OBJ_Positions *p = [playerPositionsARR objectAtIndex:indexPath.row];
    NSLog(@"Selected Player IS %@",p.playerName);
}

#pragma mark - MOVE COLLECTION VIEW CELLS

-(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    return YES;
}

-(void)dragPlayer:(UILongPressGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateBegan) {
        NSLog(@"State Began");
        CGPoint point = [sender locationInView:CV_playerPositions];
        originalCellIndex = [CV_playerPositions indexPathForItemAtPoint:point];
        if (originalCellIndex) {
            UICollectionViewCell *cell = [CV_playerPositions cellForItemAtIndexPath:originalCellIndex];

        beginView =  [cell.contentView viewWithTag:cell.tag];

            beginView.backgroundColor = [UIColor greenColor];
            [beginView removeFromSuperview];

            beginView.center = [CV_playerPositions convertPoint:point toView:self.view];
            originalStartPoint = beginView.center;
            [self.view addSubview:beginView];
           [self.view bringSubviewToFront:beginView];

            OBJ_Players *pd = [playerPositionsARR objectAtIndex:originalCellIndex.row];

            NSLog(@"SELECT PLAYER NAME IS - %@",pd.playerName);
            return;
        }
    }

    if (sender.state == UIGestureRecognizerStateChanged) {
        NSLog(@"State Changed");
        if (!beginView)
            return;

        CGPoint location = [sender locationInView:self.view];
        CGPoint translation;

        translation.x = location.x - originalStartPoint.x;
        translation.y = location.y - originalStartPoint.y;
        CGAffineTransform theTransform = beginView.transform;
        theTransform.tx = translation.x;
        theTransform.ty = translation.y;
        beginView.transform = theTransform;

        return;
    }

    if (sender.state == UIGestureRecognizerStateEnded) {
        NSLog(@"STATE ENDED");

        if (beginView) {
            CGPoint epoint = [sender locationInView:CV_playerPositions];
            endCellIndex = [CV_playerPositions indexPathForItemAtPoint:epoint];
            if(endCellIndex)
            {
                OBJ_Positions *p = [playerPositionsARR objectAtIndex:endCellIndex.row];

                NSLog(@"POSITION IS - %@ AND PLAYER DRAGGED IS %@",p.position,p.playerName);
                [self moveItemAtIndexPath:originalCellIndex toIndexPath:endCellIndex];
                [beginView removeFromSuperview];

                return;

            }
        }
    }
}

- (IBAction)movingPlayer:(id)sender {
    [self dragPlayer:sender];
}

Answer 1

我相信这个链接正是你要找的。 https://github.com/lxcid/LXReorderableCollectionViewFlowLayout

它扩展UICollectionViewFlowLayout以支持细胞的重新排序。类似于在iBook中长按和平移书籍。