iOS 长按移动UICollectionView中Cell的位置

在使用苹果手机的时候，大家可能会发现这样的一种操作效果：

UICollectionView.gif

就是在一个UICollectionView上，长按某一个cell，就能移动它，并且能够放在新的位置。这个方法就用到了UICollectionVIew的移动方法了，话不多说，直接上代码：

#import "ViewController.h"
#import "CollectionViewCell.h"
#import "ImageModel.h"

@interface ViewController () <UICollectionViewDataSource, UICollectionViewDelegate>

/// collectionView
@property (nonatomic, strong) UICollectionView *collectionView;
/// 数据
@property (nonatomic, strong) NSMutableArray<ImageModel *> *imageModels;
/// 是否移动
@property (nonatomic, assign) BOOL isBeganMove;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //获取数据
    [self getDatas];
    
    //注册cell
    [self.collectionView registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:@"CollectionViewCell"];
    
    [self.collectionView reloadData];
}

/// 创建假数据
-(void)getDatas {
    self.imageModels = [NSMutableArray array];
    
    for (int index = 0; index < 10; index ++) {
        ImageModel *model = [[ImageModel alloc] init];
        model.imageName = [NSString stringWithFormat:@"image%d", index];
        
        [self.imageModels addObject:model];
    }
}

#pragma mark - 手势事件
-(void)moveCollectionViewCell:(UILongPressGestureRecognizer *)gesture {
    switch (gesture.state) {
        case UIGestureRecognizerStateBegan: {
            if (!self.isBeganMove) {
                self.isBeganMove = YES;
                //获取点击的cell的indexPath
                NSIndexPath *selectedIndexPath = [self.collectionView indexPathForItemAtPoint:[gesture locationInView:self.collectionView]];
                
                //开始移动对应的cell
                [self.collectionView beginInteractiveMovementForItemAtIndexPath:selectedIndexPath];
            }
            break;
        }
        case UIGestureRecognizerStateChanged: {
            //移动cell
            [self.collectionView updateInteractiveMovementTargetPosition:[gesture locationInView:self.collectionView]];
            break;
        }
        case UIGestureRecognizerStateEnded: {
            self.isBeganMove = false;
            //结束移动
            [self.collectionView endInteractiveMovement];
            break;
        }
        default:
            [self.collectionView cancelInteractiveMovement];
            break;
    }
}

#pragma mark - UICollectionViewDataSource/UICollectionViewDelegate
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return self.imageModels.count;
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CollectionViewCell" forIndexPath:indexPath];
    
    cell.imageView.image = [UIImage imageNamed:self.imageModels[indexPath.row].imageName];
    
    //添加长按手势
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(moveCollectionViewCell:)];
    [cell addGestureRecognizer:longPress];
    
    return cell;
}

-(void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath {
    //处理数据（删除之前的位置数据，插入到新的位置）
    ImageModel *selectModel = self.imageModels[sourceIndexPath.item];
    [self.imageModels removeObjectAtIndex:sourceIndexPath.item];
    [self.imageModels insertObject:selectModel atIndex:destinationIndexPath.item];

    //此处可以根据需要，上传给后台目前数据的顺序
}

#pragma mark - 懒加载
-(UICollectionView *)collectionView {
    if (!_collectionView) {
        UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
        layout.minimumInteritemSpacing = 10;
        layout.minimumLineSpacing = 10;
        layout.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);
        layout.itemSize = CGSizeMake([UIScreen mainScreen].bounds.size.width / 2.f - 20.f, [UIScreen mainScreen].bounds.size.width / 2.f - 20.f);
        
        _collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout];
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.backgroundColor = [UIColor whiteColor];
        [self.view addSubview:_collectionView];
    }
    
    return _collectionView;
}

@end

这些代码其实说的很明白了。大家发现，其实在移动的过程中，相当不停的调用UICollectionView的移动cell的方法，并且不停地变化着数据数组的顺序。这样就可以保证在改变cell的位置的同时，也改变了数据的顺序。

看到代码之后，大家就会发现，这个需求简直太容易了，喜欢的话就点个赞吧。