UICollectionView及其代理方法

先上代碼：

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.navigationItem.title = @"集合視圖";
    
    UICollectionViewFlowLayout *collectionVIewlayout = [[UICollectionViewFlowLayout alloc]init];
    //設置單元格的大小
    [collectionVIewlayout setItemSize:CGSizeMake(50, 50)];
    //設施最小行間距
    [collectionVIewlayout setMinimumLineSpacing:20];
    //設置最小列間距
    [collectionVIewlayout setMinimumInteritemSpacing:20];
    //設置分區間隔
    [collectionVIewlayout setSectionInset:UIEdgeInsetsMake(20, 20, 20, 20)];
    //集合視圖的使用
    UICollectionView *collectionView = [[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:collectionVIewlayout];
    [collectionView setBackgroundColor:[UIColor whiteColor]];
    //註冊Item
    [collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"item"];
    //註冊頭部視圖
    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headView"];
    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footView"];
    //指定代理（和表視圖一樣）
    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;
}

//定義Item
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    //從重用隊列中卻出cell；
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"item" forIndexPath:indexPath];
    //獲取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(@"我被點了");
}

//頭尾視圖
-(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;
}
//定義頭視圖的大小
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{
    return CGSizeMake(100, 100);
}
//定義尾視圖的大小
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section{
    return CGSizeMake(50, 30);
}
//邊緣距離
-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{
    
}
//最小行間距
-(CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{
    
}
//最小列間距
-(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

記住其常用的屬性和代理方法。