UICollectionView及其代理方法

先上代码：

@implementation RootViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    self.navigationItem.title = @"集合视图";        UICollectionViewFlowLayout *collectionVIewlayout = [[UICollectionViewFlowLayout alloc]init];    //设置单元格的大小    [collectionVIewlayout setItemSize:CGSizeMake(50, 50)];    //设施最小行间距    [collectionVIewlayout setMinimumLineSpacing:20];    //设置最小列间距    [collectionVIewlayout setMinimumInteritemSpacing:20];    //设置分区间隔    [collectionVIewlayout setSectionInset:UIEdgeInsetsMake(20, 20, 20, 20)];    //集合视图的使用    UICollectionView *collectionView = [[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:collectionVIewlayout];    [collectionView setBackgroundColor:[UIColor whiteColor]];    //注册Item    [collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"item"];    //注册头部视图    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headView"];    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footView"];    //指定代理（和表视图一样）    collectionView.delegate = self;    collectionView.dataSource = self;    [self.view addSubview:collectionView];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}#pragma mark - 代理方法-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{    return 2;}-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 10;}//定义Item-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    //从重用队列中却出cell；    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"item" forIndexPath:indexPath];    //获取cell的位置信息    NSLog(@"section--%ld--%ld",indexPath.item,indexPath.section);        [cell setBackgroundColor:[UIColor greenColor]];    return cell;}-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{    if (indexPath.item == 0) {        return CGSizeMake(80, 80);    }else{        return CGSizeMake(50, 50);    }}-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    NSLog(@"我被点了");}//头尾视图-(UICollectionReusableView*)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{        if ([kind isEqualToString:UICollectionElementKindSectionFooter]) {        UICollectionReusableView *footView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footView" forIndexPath:indexPath];        [footView setBackgroundColor:[UIColor blueColor]];        return footView;    }else{        UICollectionReusableView *headView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headView" forIndexPath:indexPath];        [headView setBackgroundColor:[UIColor orangeColor]];        return headView;    }    return nil;}//定义头视图的大小-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{    return CGSizeMake(100, 100);}//定义尾视图的大小-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section{    return CGSizeMake(50, 30);}//边缘距离-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{    }//最小行间距-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{    }//最小列间距-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{    }/*#pragma mark - Navigation// In a storyboard-based application, you will often want to do a little preparation before navigation- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {    // Get the new view controller using [segue destinationViewController].    // Pass the selected object to the new view controller.}*/@end

记住其常用的属性和代理方法。