UICollectionView 集合视图

           UICollectionView 和 UICollectionViewController 类是iOS6 新引进的API，用于展示集合视图，布局更加灵活，可实现多列布局，用法类似于UITableView 和 UITableViewController 类.

- (void)viewDidLoad{    [super viewDidLoad];// Do any additional setup after loading the view, typically from a nib.    //self.view.backgroundColor = [UIColor redColor];        UICollectionViewFlowLayout * layout = [[UICollectionViewFlowLayout alloc]init];    // 设置滚动方向    layout.scrollDirection = UICollectionViewScrollDirectionVertical;    // 设置layout块的大小,决定cell的大小    //layout.itemSize = CGSizeMake(100, 100);    //layout.minimumLineSpacing = 100;    //layout.minimumInteritemSpacing = 100;    //layout.headerReferenceSize = CGSizeMake(320, 40);    //layout.footerReferenceSize = CGSizeMake(320, 80);    //layout.sectionInset = UIEdgeInsetsMake(20, 20, 20, 20);        UICollectionView * collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 20, ScreenWidth, ScreenHeight-20) collectionViewLayout:layout];    collectionView.delegate = self;    collectionView.dataSource = self;    // 注册cell的类型,才能实现cell重用    [collectionView registerClass:[HMTMyCustomCollectionCell class] forCellWithReuseIdentifier:@"cell"];            [self.view addSubview:collectionView];}//  设置分区- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{    return 2;}//  定义每个分区上的元素个数- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 10;}//  设置元素内容- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    static NSString * cellIdentifier = @"cell";    HMTMyCustomCollectionCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];        cell.backgroundColor = [UIColor cyanColor];    cell.showLabel.text = [NSString stringWithFormat:@"%ld,%ld",indexPath.section,indexPath.row];        return cell;}//  设置每个元素大小- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{//    if (indexPath.row % 2 == 0) {//        //        return CGSizeMake(100, 100);//    } else {//        //        return CGSizeMake(50, 150);//    }    return CGSizeMake(100, 50);}//  定义每个元素的margin(边缘 上-左-下-右)- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{    return UIEdgeInsetsMake(0, 0, 0, 0);}//  定义单元格所在行line之间的距离,前一行和后一行的距离- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{        return 20;}//  定义每个单元格相互之间的距离- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{        return 0;}//  设置页眉(水平滑动的时候设置width,垂直滑动的时候设置height)- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{        return CGSizeMake(10, 100);}//  设置页脚(水平滑动的时候设置width,垂直滑动的时候设置height)- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section{    return CGSizeMake(10, 10);}//  点击元素响应方法-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{}/*******************************************自定义Cell***************************************************************/- (void)createShowLabel{    _showLabel = [[UILabel alloc]initWithFrame:CGRectMake(10, 10, self.bounds.size.width-20, self.bounds.size.height-20)];    _showLabel.backgroundColor = [UIColor redColor];    [self.contentView addSubview:_showLabel];    [_showLabel release];    }//  重点:防止cell错乱- (void)layoutSubviews{    [super layoutSubviews];    _showLabel.frame = CGRectMake(10, 10, self.bounds.size.width-20, self.bounds.size.height-20);    }

@附加:可能最不好理解的就是那个上-左-下-右了,给出2张图作参考

@补充:(storyboard中无需注册)

//设置headerView的高度- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section//设置sectionHeaderView- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath //注册某种类型的headerView    [self.collectionView registerClass:[RecipeCollectionHeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView"];