ios - UICollectionView 中的单元格重叠

Question

我正在使用一个 ViewController，我在其中添加了一个 UICollectionView:

UICollectionViewFlowLayout *collectionViewFlowLayout = [[UICollectionViewFlowLayout alloc] init];
[collectionViewFlowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
[collectionViewFlowLayout setMinimumInteritemSpacing:2];
[collectionViewFlowLayout setMinimumLineSpacing:4];
[collectionViewFlowLayout setHeaderReferenceSize:CGSizeMake(320, 30)];

CGRect collectionViewFrame = self.view.bounds;
self.collectionView = [[UICollectionView alloc] initWithFrame:collectionViewFrame collectionViewLayout:collectionViewFlowLayout];
self.collectionView.autoresizingMask = UIViewAutoresizingFlexibleHeight;

self.collectionView.delegate = self;
self.collectionView.dataSource = self;

[self.collectionView registerClass:[MyCollectionViewCell class] forCellWithReuseIdentifier:myCellIdentifier];

[self.view addSubview:self.collectionView];

这就是我初始化自定义单元格对象的方式(我确保每个单元格的框架填满屏幕的整个宽度，以便单元格在 UICollectionView 中一个接一个地垂直呈现):

CGSize mySize = CGSizeMake(320, 158);
self.myTitle = [[UILabel alloc ] initWithFrame:CGRectMake(0, 0, mySize.width, mySize.height)];
[self.myTitle setTextColor:[UIColor whiteColor]];
[self.myTitle setBackgroundColor:[UIColor greenColor]];
[self.myTitle setTextAlignment:NSTextAlignmentLeft];
[self.myTitle setNumberOfLines:1];
[self.myTitle setText:@"My Title"];
[self addSubview:self.myTitle];

这就是我在 initWithNibName 中初始化单元格框架的方式:

CGSize mySize = CGSizeMake(320, 158);
self = [super initWithFrame:CGRectMake(0, 0, mySize.width, mySize.height)];

这是我的 cellForItemAtIndexPath 代码:

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = (UICollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:myCellIdentifier forIndexPath:indexPath];

    return cell;
}

现在我有四个这样的单元格，但它们是重叠的。我究竟做错了什么？谢谢!

Answer 1

实现 UICollectionViewFlowLayout 委托(delegate)调用:

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
return CGSizeMake(320, 158);
}

或者由于所有尺寸都是恒定的，只需像这样在 Flow 布局中指定尺寸:

UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc]init];
flowLayout.itemSize = CGSizeMake(320, 158);