手把手CollectionView

最新推荐文章于 2021-07-20 14:52:04 发布

原创最新推荐文章于 2021-07-20 14:52:04 发布 · 360 阅读

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本文介绍了一个使用UICollectionView展示不同布局和数据源方法的iOS应用案例。通过UICollectionViewFlowLayout设置了垂直滚动方向、间距及填充，并实现了三个不同的section来展示不同类型的内容。每个section有不同的cell数量和尺寸，还展示了如何注册cell和footer视图。

@interface RootViewController ()<UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout>
@end

@implementation RootViewController {
    UICollectionView *mainCollectionView;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    layout.scrollDirection = UICollectionViewScrollDirectionVertical;

    layout.minimumLineSpacing = 0;
    layout.minimumInteritemSpacing = 0;

    layout.sectionInset = UIEdgeInsetsMake(4, 8, 4, 8);

    mainCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 20, SCREEN_WIDTH, [UIScreen mainScreen].bounds.size.height-20)collectionViewLayout:layout];
    mainCollectionView.backgroundColor = [UIColor whiteColor];
    mainCollectionView.dataSource = self;
    mainCollectionView.delegate = self;
    [self.view addSubview:mainCollectionView];

    [mainCollectionView registerNib:[UINib nibWithNibName:@"MyCollectionViewCell" bundle:[NSBundle mainBundle]] forCellWithReuseIdentifier:@"CELL"];
    [mainCollectionView registerNib:[UINib nibWithNibName:@"FooterView" bundle:[NSBundle mainBundle]] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"F"];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 3;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    switch (section) {
        case 0:
            return 8;
            break;
        case 1:
            return 2;
            break;
        case 2:
            return 3;
            break;
        default:
            break;
    }
    return 0;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    MyCollectionViewCell *cell = (MyCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath];

    if (indexPath.section == 0) {
        cell.mainLabel.backgroundColor = [UIColor redColor];
        cell.mainLabel.text = [NSString stringWithFormat:@"%ld", indexPath.row+1];

        cell.mainLabel.layer.cornerRadius = ((SCREEN_WIDTH-16)/4-16)/2;
        cell.mainLabel.clipsToBounds = YES;
    }
    else if (indexPath.section == 1) {
        cell.mainLabel.backgroundColor = [UIColor greenColor];
        cell.mainLabel.text = [NSString stringWithFormat:@"Group %ld Item %ld", indexPath.section+1 ,indexPath.row+1];
    }
    else {
        cell.mainLabel.backgroundColor = [UIColor blueColor];
        cell.mainLabel.text = [NSString stringWithFormat:@"Group %ld Item %ld", indexPath.section+1 ,indexPath.row+1];

        NSIndexPath *firstIndexPath = [NSIndexPath indexPathForRow:0 inSection:indexPath.section];
        UICollectionViewCell *firstCell = [collectionView cellForItemAtIndexPath:firstIndexPath];
        NSLog(@"%f %f", firstCell.frame.origin.x, firstCell.frame.origin.y);

        if (indexPath.row == 1) {

            cell.frame = CGRectMake(firstCell.frame.origin.x + firstCell.frame.size.width, firstCell.frame.origin.y, (SCREEN_WIDTH-16)/2, 60);
        }
        else if(indexPath.row == 2) {

            cell.frame = CGRectMake(firstCell.frame.origin.x + firstCell.frame.size.width, firstCell.frame.origin.y + 60, (SCREEN_WIDTH-16)/2, 60);
        }
    }
    cell.mainLabel.textColor = [UIColor whiteColor];

    return cell;
}


- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    switch (indexPath.section) {
        case 0:
            return CGSizeMake((SCREEN_WIDTH-16)/4, (SCREEN_WIDTH-16)/4);
            break;
        case 1:
            return CGSizeMake(SCREEN_WIDTH-16, 60);
            break;
        case 2:

            if (indexPath.row == 0) {
                return CGSizeMake((SCREEN_WIDTH-16)/2, 120);
            }
            else{
                return CGSizeMake((SCREEN_WIDTH-16)/2, 0);
            }
            break;
        default:
            break;
    }
    return CGSizeMake(0, 0);
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
    if (kind == UICollectionElementKindSectionFooter) {
        FooterView *ff = (FooterView *)[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"F" forIndexPath:indexPath];
        return ff;
    }
    return nil;
}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section {

    return CGSizeMake([UIScreen mainScreen].bounds.size.width, 50);
}
@end