#import "ViewController.h"

#import "GoodsCollectionViewCell.h"

@interface ViewController ()

@property(nonatomic,strong)NSMutableArray *dataArray;

@end

@implementation ViewController

- (void)viewDidLoad

{

    [super viewDidLoad];

    self.view.backgroundColor = [UIColor lightGrayColor];

    _dataArray = [NSMutableArray array];

    for (int i = ; i < ; i ++) {

        [_dataArray addObject:[NSString stringWithFormat:@"%d",i]];

    }

    //确定是水平滚动，还是垂直滚动

    UICollectionViewFlowLayout *flowLayout=[[UICollectionViewFlowLayout alloc] init];

    flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;

    self.collectionView=[[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:flowLayout];

    self.collectionView.dataSource=self;

    self.collectionView.delegate=self;

    [self.collectionView setBackgroundColor:[UIColor clearColor]];

    //注册Cell，必须要有

    [self.collectionView registerNib:[UINib nibWithNibName:@"GoodsCollectionViewCell" bundle:nil] forCellWithReuseIdentifier:@"GoodsCollectionViewCell"];

    [self.collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];

    [self.view addSubview:self.collectionView];

}

#pragma mark -- UICollectionViewDataSource

//定义展示的UICollectionViewCell的个数

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section

{

    return ;

}

//定义展示的Section的个数

-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView

{

    return ;

}

//每个UICollectionView展示的内容

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath

{

    GoodsCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"GoodsCollectionViewCell" forIndexPath:indexPath];

    cell.goodsImageView.image = [UIImage imageNamed:_dataArray[indexPath.row]];

    cell.backgroundColor = [UIColor whiteColor];

    return cell;

}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

{

    UICollectionReusableView *headReusableView;

    //此处是headerView

    if (kind == UICollectionElementKindSectionHeader) {

        headReusableView = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"header" forIndexPath:indexPath];

        //防止复用时候重复添加title

        [headReusableView.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];

        if (indexPath.section == ) {

            UIView *headerADView = [[ UIView alloc]initWithFrame:CGRectMake(, , self.view.frame.size. width, )];

            headerADView.backgroundColor = [UIColor yellowColor];

            UILabel *titleADLabel = [[UILabel alloc]initWithFrame:CGRectMake(, , self.view.frame.size. width - , )];

            titleADLabel.text = @"这个是广告位";

            UILabel *titleLabel = [[UILabel alloc]initWithFrame:CGRectMake(, , self.view.frame.size. width - , )];

            titleLabel.text = @"推荐商品";

            headReusableView.backgroundColor = [UIColor colorWithWhite:. alpha:];

            [headerADView addSubview:titleADLabel];

            [headReusableView addSubview:headerADView];

            [headReusableView addSubview:titleLabel];

        }else{

            UILabel *titleLabel = [[UILabel alloc]initWithFrame:CGRectMake(, , self.view.frame.size. width - , )];

            titleLabel.text = @"推荐商品";

            headReusableView.backgroundColor = [UIColor colorWithWhite:. alpha:];

            [headReusableView addSubview:titleLabel];

        }

    }

    return headReusableView;

}

//执行的 headerView 代理  返回 headerView 的高度

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section

{

    if (section == ) {

        return CGSizeMake(,  + );

    }

    return CGSizeMake(, );

}

#pragma mark --UICollectionViewDelegateFlowLayout

//定义每个Item 的大小

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath

{

    return CGSizeMake(self.view.frame.size.width / 3.0, );

}

//定义每个UICollectionView 的 margin

-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section

{

    return UIEdgeInsetsMake(, , , );

}

#pragma mark --UICollectionViewDelegate

//UICollectionView被选中时调用的方法

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath

{

    GoodsCollectionViewCell * cell = (GoodsCollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];

    //临时改变个颜色，看好，只是临时改变的。如果要永久改变，可以先改数据源，然后在cellForItemAtIndexPath中控制。（和UITableView差不多吧！O(∩_∩)O~）

    cell.backgroundColor = [UIColor greenColor];

}

//返回这个UICollectionView是否可以被选择

-(BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath

{

    return YES;

}

// 两个cell之间的最小间距，是由API自动计算的，只有当间距小于该值时，cell会进行换行

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section

{

    return ;

}

// 两行之间的最小间距

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section

{

    return ;

}

@end