UICollectionViewDemo

UICollectionViewDemo,the basic how to use

.h:

UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout

UICollectionViewFlowLayout

创建UICollectionView之前一定要先配置好UICollectionViewFlowLayout

    CFL                         = [[UICollectionViewFlowLayout alloc]init];
    CFL.minimumInteritemSpacing = 1;//每个items之间的间隙
    CFL.minimumLineSpacing      = 1;//每行items之间的间隙

UICollectionView

    CV            = [[UICollectionView alloc]initWithFrame:self.view.frame collectionViewLayout:CFL];
    CV.dataSource = self;
    CV.delegate   = self;
    [CV registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"coll"];
    [self.view addSubview:CV];

实现代理方法

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 5000;
}

//设置cell，与tableview类似

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"coll" forIndexPath:indexPath];
    
    //随机背景色
    CGFloat red     = arc4random()%256/255.0;
    CGFloat green   = arc4random()%256/255.0;
    CGFloat blue    = arc4random()%256/255.0;
    cell.backgroundColor = [UIColor colorWithRed:red green:green blue:blue alpha:1.0];
    
    return cell;
}

//item大小

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    return CGSizeMake(
                      (screenWidth-CFL.minimumInteritemSpacing*(countOfRowItem+1))/countOfRowItem,
                      (screenWidth-CFL.minimumInteritemSpacing*(countOfRowItem+1))/countOfRowItem);
}

//section的edgeInserts

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    return UIEdgeInsetsMake(CFL.minimumInteritemSpacing,
                            CFL.minimumInteritemSpacing,
                            CFL.minimumInteritemSpacing,
                            CFL.minimumInteritemSpacing);
}