iOS UICollectionView简单使用

UICollectionView 和 UICollectionViewController 类是iOS6 新引进的API，用于展示集合视图，布局更加灵活，可实现多列布局，用法类似于UITableView 和 UITableViewController 类。

使用UICollectionView 必须实现UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout这三个协议。

下面给出一些常用方法，具体的使用可以参考Demo:点我下载  苹果官方Demo:点我下载

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.title = @"UICollectionView学习";

    //通过Nib生成cell，然后注册 Nib的view需要继承 UICollectionViewCell
    [self.collectionView registerNib:[UINib nibWithNibName:@"SQCollectionCell" bundle:nil] forCellWithReuseIdentifier:kcellIdentifier];

    //注册headerView Nib的view需要继承UICollectionReusableView
    [self.collectionView registerNib:[UINib nibWithNibName:@"SQSupplementaryView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:kheaderIdentifier];
    //注册footerView Nib的view需要继承UICollectionReusableView
    [self.collectionView registerNib:[UINib nibWithNibName:@"SQSupplementaryView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:kfooterIdentifier];
    //
    self.collectionView.allowsMultipleSelection = YES;//默认为NO,是否可以多选

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
#pragma mark -CollectionView datasource
//section
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 2;
}
//item个数
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 6;

}

// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    //重用cell
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kcellIdentifier forIndexPath:indexPath];
    //赋值
    UIImageView *imageView = (UIImageView *)[cell viewWithTag:1];
    UILabel *label = (UILabel *)[cell viewWithTag:2];
    NSString *imageName = [NSString stringWithFormat:@"%ld.JPG",(long)indexPath.row];
    imageView.image = [UIImage imageNamed:imageName];
    label.text = imageName;

    cell.backgroundColor = [UIColor redColor];
    return cell;

}
// The view that is returned must be retrieved from a call to -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath:
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{

    NSString *reuseIdentifier;
    if ([kind isEqualToString: UICollectionElementKindSectionFooter ]){
        reuseIdentifier = kfooterIdentifier;
    }else{
        reuseIdentifier = kheaderIdentifier;
    }

    UICollectionReusableView *view =  [collectionView dequeueReusableSupplementaryViewOfKind :kind   withReuseIdentifier:reuseIdentifier   forIndexPath:indexPath];

    UILabel *label = (UILabel *)[view viewWithTag:1];
    if ([kind isEqualToString:UICollectionElementKindSectionHeader]){
        label.text = [NSString stringWithFormat:@"这是header:%d",indexPath.section];
    }
    else if ([kind isEqualToString:UICollectionElementKindSectionFooter]){
        view.backgroundColor = [UIColor lightGrayColor];
        label.text = [NSString stringWithFormat:@"这是footer:%d",indexPath.section];
    }
    return view;
}
//定义每个UICollectionViewCell 的大小
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    return CGSizeMake(60, 80);
}
//定义每个Section 的 margin
-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    return UIEdgeInsetsMake(15, 15, 5, 15);//分别为上、左、下、右
}
//返回头headerView的大小
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{
    CGSize size={320,45};
    return size;
}
//返回头footerView的大小
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
{
    CGSize size={320,45};
    return size;
}
//每个section中不同的行之间的行间距
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
{
    return 10;
}
//每个item之间的间距
//- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
//{
//    return 100;
//}
//选择了某个cell
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
    [cell setBackgroundColor:[UIColor greenColor]];
}
//取消选择了某个cell
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
    [cell setBackgroundColor:[UIColor redColor]];
}