Question

虽然显示UICollectionViewCell，但[collectionView visibleCells]返回nil。

- (void)viewDidLoad{
    self.collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, 320, 568) collectionViewLayout:flowLayout];
    self.collectionView.delegate = self;
    self.collectionView.dataSource = self;
    [self.collectionView registerClass:[CustomCell class] forCellWithReuseIdentifier:@"Cell"];
    [self.view addSubview:self.collectionView];

    NSLog(@"%d", [[self.collectionView visibleCells] count]);
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CustomCell* cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
    return cell;
}

你有什么想法吗？

Answer 1

问题是由重装尚未完成引起的。解决方案是： 1. [collectionView reloadData]; 2. ** [collectionView layoutIfNeeded]; 3.得到你的 - ＆gt; [collectionView visibleCells];

Answer 2

在视图控制器中尝试此操作

- (void) viewDidLayoutSubviews {
   NSLog(@"%d", [[self.collectionView visibleCells] count]);
}

Answer 3

尝试添加此内容：

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    collectionView?.collectionViewLayout.invalidateLayout()
}

UICollectionView visibleCells返回nil

3 个答案: