collectionView的使用总结

- (void)initSubViews
{
    UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc]init];
    
    //flowLayout.itemSize = CGSizeMake(([UIScreen mainScreen].bounds.size.width-15)/2, 200);
    // 设置行的最小间距
//    flowLayout.minimumInteritemSpacing = 10;
//    // 设置列最小行间距
//    flowLayout.minimumLineSpacing = 10;
    // 设置cell之间的上，左，下，右
//    flowLayout.sectionInset = UIEdgeInsetsMake(0, 10, 0, 10);
    // 滚动方向
    flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;
    //    flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:flowLayout];
    // 如果未设置背景颜色是黑色设置背景颜色
    self.collectionView.backgroundColor = [UIColor whiteColor];
    // 设置代理
    self.collectionView.delegate = self;
    self.collectionView.dataSource = self;
    [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"CELL"];

    
    [self.view addSubview:self.collectionView];
    
    UIView *headView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 200)];
    headView.backgroundColor = [UIColor yellowColor];
   // [self.collectionView addSubview:headView];

}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    //    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath];
    UICollectionView *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath];
    
    cell.backgroundColor = [UIColor colorWithRed:arc4random()%256/256.0 green:arc4random()%256/256.0 blue:arc4random()%256/256.0 alpha:1];
    
    
    return cell;
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    
    return 10;
}
#pragma mark - 设置collectionView的大小
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{

        //展开
    return CGSizeMake(([UIScreen mainScreen].bounds.size.width-40)/3, 150);
}
////设置单元格间的横向间距
//- (CGFloat) collectionView:(UICollectionView *)collectionView
//                    layout:(UICollectionViewLayout *)collectionViewLayout
//minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
//{
//    return 5.0f;
//}
////设置纵向的行间距
//- (CGFloat) collectionView:(UICollectionView *)collectionView
//                    layout:(UICollectionViewLayout *)collectionViewLayout
//minimumLineSpacingForSectionAtIndex:(NSInteger)section
//{
//    return 25;
//}
//2: 设置section间的大小

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

{

      return UIEdgeInsetsMake(0, 10, 0, 10);
}