【项目】UICollectionView 对象自定

陈述一下简单流程：

1.首先定义：UICollectionViewFlowLayout

2.初始化UICollectionView

3.注册复用的cell，定义她们的reuseIndefinite

4.注册UICollectionView的delegate和DataSource代理

5.完成代理，ok

代码：

- (UICollectionView *)collectionView
{
    if (!_collectionView)
    {
        UICollectionViewFlowLayout * layout = [[UICollectionViewFlowLayout alloc] init];
        layout.minimumLineSpacing      = I_P_SP;
        layout.minimumInteritemSpacing = I_P_I_SP;
        layout.scrollDirection         = UICollectionViewScrollDirectionHorizontal;

        _collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(, , self.width, )  collectionViewLayout:layout];
        _collectionView.backgroundColor = def_color_white;
        [_collectionView registerClass:[IssuePhotosViewCell class] forCellWithReuseIdentifier:kPhotoCellIdentifier];
        [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:kAddCellIdentifier];

        _collectionView.delegate                       = self;
        _collectionView.dataSource                     = self;
        _collectionView.showsHorizontalScrollIndicator = NO;
        _collectionView.showsVerticalScrollIndicator   = NO;

        [self addSubview:_collectionView];
    }
    return _collectionView;
}

UICollectionView的Lazy Load

#pragma mark - UICollectionViewDelegate / DataSource / FlowLayout

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    , );
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    // TODO 图片浏览器

    NSLog(@"%ld",(long)[indexPath row]);
}

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

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row == [self.assetsArray count])
    {
        UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:kAddCellIdentifier forIndexPath:indexPath];
        [cell.contentView addSubview:self.addButton];
        return cell;
    }
    else
    {
        IssuePhotosViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:kPhotoCellIdentifier forIndexPath:indexPath];
        cell.asset                 = [self.assetsArray objectAtIndex:indexPath.row];
        cell.indexPath             = indexPath;
        cell.deletePhotoButton.tag = indexPath.row;
        [cell.deletePhotoButton addTarget:self action:@selector(deleteView:) forControlEvents:UIControlEventTouchUpInside];

        return cell;
    }

UICollectionView的代理实现

复用问题，只要把界面和数据分开处理即可，界面初始化写在自定cell或者系统cell的初始化中，数据则每次重新更新即可