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UICollectionView 简单使用

UICollectionView 简单使用

作者: 忆白i | 来源:发表于2017-09-16 10:09 被阅读8次
    #import "ViewController.h"
    
    #define _CELL @ "acell"
    
    @interface ViewController ()< UICollectionViewDataSource , UICollectionViewDelegate , UICollectionViewDelegateFlowLayout >
    
    @property (nonatomic , strong) UICollectionView * collectionView;
    @property (nonatomic , strong) NSMutableArray *arr;
    @property (nonatomic , assign) CGFloat Height;
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
        [self arr];
        [self collectionView];
    }
    
    #pragma mark - lazyload
    
    -(UICollectionView *)collectionView{
        if (_collectionView == nil) {
            NSInteger i = _arr.count-1;
            _Height       = 20+(i/4+1)*20+(i/4)*10;
            //先实例化一个层
            UICollectionViewFlowLayout *layout=[[ UICollectionViewFlowLayout alloc ] init ];
            [layout setScrollDirection:UICollectionViewScrollDirectionVertical];
            
            //创建UICollectionView大小
            _collectionView=[[ UICollectionView alloc ] initWithFrame:CGRectMake(0, 64, self.view.frame.size.width, _Height) collectionViewLayout :layout];
            //注册Cell类
            [_collectionView registerClass :[ UICollectionViewCell class ] forCellWithReuseIdentifier : _CELL ];
            _collectionView. delegate = self ;
            _collectionView. dataSource = self ;
            _collectionView.backgroundColor = [UIColor grayColor];
            [ self . view addSubview :_collectionView];
        }
        return _collectionView;
    }
    
    -(NSMutableArray *)arr{
        if (_arr==nil) {
            _arr =  [[NSMutableArray alloc]initWithObjects:@"父母之魂1",@"父母之魂2",@"父母之魂3",@"父母之魂4",@"父母之魂5",@"父母之魂6",@"父母之魂7",@"父母之魂8",@"父母之魂1",@"父母之魂2",@"父母之魂3",@"父母之魂4",@"父母之魂5",@"父母之魂6",@"父母之魂7",@"父母之魂8",nil];
        }
        return _arr;
    }
    
    #pragma mark --UICollectionViewDataSource
    
    //定义展示的UICollectionViewCell的个数
    -( NSInteger )collectionView:( UICollectionView *)collectionView numberOfItemsInSection:( NSInteger )section{
        return _arr.count ;
    }
    
    //定义展示的Section的个数
    -( NSInteger )numberOfSectionsInCollectionView:( UICollectionView *)collectionView{
        return 1 ;
    }
    
    //每个UICollectionView展示的内容
    -( UICollectionViewCell *)collectionView:( UICollectionView *)collectionView cellForItemAtIndexPath:( NSIndexPath *)indexPath{
        UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier : _CELL forIndexPath :indexPath];
        
        UIButton * btn = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 70, 20)];
        [btn setTitleColor:[UIColor blackColor] forState:(UIControlStateNormal)];
        btn.backgroundColor = [UIColor yellowColor];
        [btn setTitle:[_arr objectAtIndex:indexPath.row]  forState:(UIControlStateNormal)];
        [cell.contentView addSubview:btn];
        btn.userInteractionEnabled = NO;
        
        return cell;
    }
    
    #pragma mark --UICollectionViewDelegate
    
    //UICollectionView被选中时调用的方法
    -( void )collectionView:( UICollectionView *)collectionView didSelectItemAtIndexPath:( NSIndexPath *)indexPath{
        NSLog(@"%ld",(long)indexPath.row);
        [_arr removeObjectAtIndex:indexPath.row];
        [collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
        //删除后再计算collection的高度
        NSInteger i = _arr.count-1;
        _Height       = 20+(i/4+1)*20+(i/4)*10;
        _collectionView.frame = CGRectMake(0, 64, self.view.frame.size.width, _Height);
    }
    
    //返回这个UICollectionViewCell是否可以被选择
    -( BOOL )collectionView:( UICollectionView *)collectionView shouldSelectItemAtIndexPath:( NSIndexPath *)indexPath{
        return YES ;
    }
    
    #pragma mark --UICollectionViewDelegateFlowLayout
    //定义每个UICollectionView 的大小
    - ( CGSize )collectionView:( UICollectionView *)collectionView layout:( UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:( NSIndexPath *)indexPath{
        return CGSizeMake ( 70 , 20 );
    }
    
    //定义每个UICollectionView 的边距(次序: 上,左,下,右边)
    -( UIEdgeInsets )collectionView:( UICollectionView *)collectionView layout:( UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:( NSInteger )section{
        return UIEdgeInsetsMake ( 10 , 10 , 10 , 10 );
    }
    
    //设置单元格间的横向间距
    - (CGFloat) collectionView:(UICollectionView *)collectionView
                        layout:(UICollectionViewLayout *)collectionViewLayout
    minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{
        return (self.view.frame.size.width-10-280)/4;
    }
    
    //设置单元格间的竖向间距
    - (CGFloat) collectionView:(UICollectionView *)collectionView
                        layout:(UICollectionViewLayout *)collectionViewLayout
    minimumLineSpacingForSectionAtIndex:(NSInteger)section
    {
        return 10;
    }
    
    // 长按某item,弹出copy和paste的菜单
    - (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath
    {
        return YES;
    }
    
    // 使copy和paste有效
    - (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender
    {
        if ([NSStringFromSelector(action) isEqualToString:@"copy:"] || [NSStringFromSelector(action) isEqualToString:@"paste:"])
        {
            return YES;
        }
        
        return NO;
    }
    
    - (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender
    {
        if([NSStringFromSelector(action) isEqualToString:@"copy:"])
        {
            NSLog(@"-------------执行拷贝-------------");
            //点击长按弹出copy和paste--点击copy删除cell
            __weak typeof(self)weakSelf = self;
            [_collectionView performBatchUpdates:^{
                [weakSelf.arr removeObjectAtIndex:indexPath.row];
                [weakSelf.collectionView deleteItemsAtIndexPaths:@[indexPath]];
                //删除后再计算collection的高度
                NSInteger i = weakSelf.arr.count-1;
                weakSelf.Height       = 20+(i/4+1)*20+(i/4)*10;
                weakSelf.collectionView.frame = CGRectMake(0, 64, self.view.frame.size.width, weakSelf.Height);
                
            } completion:nil];
        }
        else if([NSStringFromSelector(action) isEqualToString:@"paste:"])
        {
            NSLog(@"-------------执行粘贴-------------");
            //点击长按弹出copy和paste--点击paste添加一个cell
            __weak typeof(self)weakSelf = self;
            [_collectionView performBatchUpdates:^{
                // 构造一个indexPath
                NSIndexPath *indePath = [NSIndexPath indexPathForItem:weakSelf.arr.count inSection:0];
                [weakSelf.collectionView insertItemsAtIndexPaths:@[indePath]]; // 然后在此indexPath处插入给collectionView插入一个item
                [weakSelf.arr addObject:@"x"]; // 保持collectionView的item和数据源一致
                //增加后再计算collection的高度
                NSInteger i = weakSelf.arr.count-1;
                weakSelf.Height       = 20+(i/4+1)*20+(i/4)*10;
                weakSelf.collectionView.frame = CGRectMake(0, 64, self.view.frame.size.width, weakSelf.Height);
                
            } completion:nil];
        }
    }
    
    @end
    
    

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