UICollectionView 没有滚动到 indexPath [英] UICollectionView isn't scrolling to indexPath

问题描述

我有一个 UICollectionView，我将 translatesAutoresizingMaskIntoConstraints 设置为 NO，并添加了一些 constraints.当我尝试将其滚动到 indexPath:

I have a UICollectionView that I set the translatesAutoresizingMaskIntoConstraints to NO, and added some constraints. When I try scrolling it to an indexPath:

[self.datesCollectionView selectItemAtIndexPath:selectedCellIndexPath animated:YES scrollPosition:UICollectionViewScrollPositionCenteredHorizontally];

然后它完全忽略它，并且不滚动.但是当我删除 translatesAutoresizingMaskIntoConstraints 时，它会滚动，但会忽略约束.

Then it completely ignores that, and doesn't scroll. But when I remove translatesAutoresizingMaskIntoConstraints, then it scrolls, but the constraints are ignored.

我的问题是，当 translatesAutoresizingMaskIntoConstraints 设置为 NO 时，如何让 collectionView 滚动到 indexPath代码>?

My question is, How can I get the collectionView to scroll to an indexPath when translatesAutoresizingMaskIntoConstraints is set to NO?

推荐答案

看了你的代码，发现了问题所在.我不确定为什么会这样，但是在应用约束后集合视图的 contentSize 为零.添加对 layoutIfNeeded 的调用到 setSelectedDate: 或 setDates: 修复了问题，

After looking at your code, I found the problem. I'm not sure why this is the case, but the contentSize of the collection view was zero after applying the constraints. Adding a call to layoutIfNeeded to either setSelectedDate: or setDates: fixed the problem,

- (void)setDates:(NSArray *)dates {
    _dates = dates;
    [self.datesCollectionView layoutIfNeeded];
    [self.datesCollectionView reloadData];

    self.selectedDate = nil;
}

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