(iOS)商城筛选

商城筛选的功能的Demo，实现如下功能：【CollectionView】初步展示数据，Section展开/折叠，以及用户选择。

先展示几张Demo界面图

分析实现步骤

1.数据

手动创建一个FiltrateItem.plist，如下图展示数据模型结构

2.懒加载初始化CollectionView，字典转模型，设置数据源

- (UICollectionView *)collectionView
{
    if (!_collectionView) {
        UICollectionViewFlowLayout *layout = [UICollectionViewFlowLayout new];
        layout.minimumLineSpacing = 10; //竖间距
        layout.itemSize = CGSizeMake((FiltrateViewScreenW - 6 * 5) / 3, 30);
        _collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.alwaysBounceVertical = YES;
        _collectionView.frame = CGRectMake(5, 0, FiltrateViewScreenW - DCMargin, ScreenH - 50);
        _collectionView.showsVerticalScrollIndicator = NO;
        
        [_collectionView registerClass:[DCAttributeItemCell class] forCellWithReuseIdentifier:DCAttributeItemCellID];//cell
        [_collectionView registerNib:[UINib nibWithNibName:NSStringFromClass([DCHeaderReusableView class]) bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:DCHeaderReusableViewID]; //头部
        [_collectionView registerClass:[DCFooterReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:DCFooterReusableViewID]; //尾部
    }
    return _collectionView;
}

#pragma mark - 筛选Item数据
- (void)setUpFiltrateData
{
    _filtrateItem = [DCFiltrateItem mj_objectArrayWithFilename:@"FiltrateItem.plist"];
}

#pragma mark - <UICollectionViewDelegate>
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    //这里默认第一组品牌展示两行数据其余展示一行数据（3个一行）
    return (_filtrateItem[section].isOpen == YES) ? self.filtrateItem[section].content.count : (section == 0) ? 6 : 3 ;
}

Demo中筛选控制的宽度我定义宏为窗口的宽度*0.8 ，每个Item的宽度为(FiltrateViewScreenW - 6 * 5) / 3，已经手动算上间距 如下图

#define FiltrateViewScreenW ScreenW * 0.8  //筛选宽宏
layout.itemSize = CGSizeMake((FiltrateViewScreenW - 6 * 5) / 3, 30); //算横间距
layout.minimumLineSpacing = 10; //竖间距

判断是否展开或关闭，判断Item是否点击，模型中加入两个BooL值

/** 用于判断当前cell是否展开 */
@property (nonatomic, assign) BOOL isOpen;
/** 是否点击 */
@property (nonatomic,assign)BOOL isSelect;

在DCAttributeItemCell中创建一个按钮，按钮contentButton尺寸为DCAttributeItemCell的尺寸，根据模型数据的isSelect数据，改变字体，背景颜色等设置，注意一定记得要把按钮的enabled设置为NO，不然点击事件就在按钮上不在DCAttributeItemCell上，didSelectItemAtIndexPath方法也就失效了

#pragma mark - Setter Getter Methods
- (void)setContentItem:(DCContentItem *)contentItem
{
    _contentItem = contentItem;
    [_contentButton setTitle:contentItem.content forState:0];
    
    if (contentItem.isSelect) { //已选
        [_contentButton setImage:[UIImage imageNamed:@"isSelectYes"] forState:0];//钩图片
        [_contentButton setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
        _contentButton.backgroundColor = [UIColor whiteColor];

        [DCSpeedy dc_chageControlCircularWith:self AndSetCornerRadius:3 SetBorderWidth:1 SetBorderColor:[UIColor redColor] canMasksToBounds:YES];
    }else{
        [_contentButton setImage:nil forState:0];
        [_contentButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        _contentButton.backgroundColor = [UIColor colorWithRed:230/255.0 green:230/255.0 blue:230/255.0 alpha:1.0];
        
        [DCSpeedy dc_chageControlCircularWith:self AndSetCornerRadius:3 SetBorderWidth:1 SetBorderColor:[UIColor clearColor] canMasksToBounds:YES];
    }
}

3.根据模型获取每组选择的数据和最后总获得数据

点击事件，通过模型讲已选的属性加入数组中，这个主意我初始化的数组内部还嵌套了多个数组层次结构类似：@[@[],@[],@[]]，这样我们根据内部数组的值来给每个Header赋值

#pragma mark - <UICollectionViewDelegate>
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{

    _filtrateItem[indexPath.section].content[indexPath.row].isSelect = !_filtrateItem[indexPath.section].content[indexPath.row].isSelect;
    
    //数组mutableCopy初始化,for循环加数组 结构大致：@[@[],@[]] 如此
    _seleArray = [@[] mutableCopy];
    for (NSInteger i = 0; i < _filtrateItem.count; i++) {
        NSMutableArray *section = [@[] mutableCopy];
        [_seleArray addObject:section];
    }
    
    //把所选的每组Item分别加入每组的数组中
    for (NSInteger i = 0; i < _filtrateItem.count; i++) {
        for (NSInteger j = 0; j < _filtrateItem[i].content.count; j++) {
            if (_filtrateItem[i].content[j].isSelect == YES) {
                [_seleArray[i] addObject:_filtrateItem[i].content[j].content];
            }else{
                [_seleArray[i] removeObject:_filtrateItem[i].content[j].content];
            }
        }
    }
    
    [collectionView reloadData];
    
}

header头部折叠展开点击Block回调和赋值已选属性

__weak typeof(self)weakSelf = self;
headerView.sectionClick = ^{
    weakSelf.filtrateItem[indexPath.section].isOpen = !weakSelf.filtrateItem[indexPath.section].isOpen; //打开取反
    
    [collectionView reloadData]; //刷新
};

//给每组的header的已选label赋值~
NSArray *array = _seleArray[indexPath.section];
NSString *selectName = @"";
for (NSInteger i = 0; i < array.count; i ++ ) {
    if (i == array.count - 1) {
        selectName = [selectName stringByAppendingString:[NSString stringWithFormat:@"%@",array[i]]];
    }else{
        selectName = [selectName stringByAppendingString:[NSString stringWithFormat:@"%@,",array[i]]];
    }
    
}

headerView.selectHeadLabel.text = (selectName.length == 0) ? @"全部" : selectName;
headerView.selectHeadLabel.textColor = ([headerView.selectHeadLabel.text isEqualToString:@"全部"]) ?  [UIColor darkGrayColor] : [UIColor redColor];

4.底部重置，确定点击事件处理

#pragma mark - 点击事件
- (void)bottomButtonClick:(UIButton *)button
{
    if (button.tag == 0) {//重置点击
        for (NSInteger i = 0; i < _filtrateItem.count; i++) {
            for (NSInteger j = 0; j < _filtrateItem[i].content.count; j++) {
                _filtrateItem[i].content[j].isSelect = NO;
                [_seleArray[i] removeAllObjects];
            }
        }
        [self.collectionView reloadData];
    }else if (button.tag == 1){//确定点击
        for (NSInteger i = 0; i < _seleArray.count; i++) {
            NSArray *array = _seleArray[i];
            NSString *selectName = @"";
            for (NSInteger i = 0; i < array.count; i ++ ) {
                if (i == array.count - 1) {
                    selectName = [selectName stringByAppendingString:[NSString stringWithFormat:@"%@",array[i]]];
                }else{
                    selectName = [selectName stringByAppendingString:[NSString stringWithFormat:@"%@,",array[i]]];
                }
                
            }
            if (selectName.length != 0) {
                NSLog(@"已选：第%zd组 的 %@",i,selectName);
            }
        }

    }
}

这样我们商品的筛选就简单的实现了，下面附上一个演示GIF

总结：Demo只是初步展示除电商类APP的筛选功能的思路，近期我将完善下，更新到我的开源电商CDDMall项目上，有需要的可以去GitHub上下载~