问题描述
在加载收集视图之前，用户设置收集视图数组中的图像数.屏幕上没有所有的单元格.我有30个单元格，屏幕上只有6个.
Before loading the collection view user sets the number of image in the array of collection view. All of the cells don't fit on the screen. I have 30 cells and only 6 on the screen.
问题:如何在加载UICollectionView时自动滚动到具有所需图像的单元格?
The question: How to scroll to the cell with desired image automatically at the load of UICollectionView?
推荐答案
我发现在viewWillAppear中滚动可能无法可靠地工作，因为集合视图尚未完成其布局.您可能滚动到错误的项目.
I've found that scrolling in viewWillAppear may not work reliably because the collection view hasn't finished it's layout yet; you may scroll to the wrong item.
我还发现在viewDidAppear中滚动会导致未滚动视图的瞬时闪烁可见.
I've also found that scrolling in viewDidAppear will cause a momentary flash of the unscrolled view to be visible.
并且，如果您每次在viewDidLayoutSubviews中滚动，则用户将无法手动滚动，因为某些集合布局会在您每次滚动时导致子视图布局.
And, if you scroll every time through viewDidLayoutSubviews, the user won't be able to manually scroll because some collection layouts cause subview layout every time you scroll.
这是我发现可靠工作的地方:
Here's what I found works reliably:
目标C:
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
// If we haven't done the initial scroll, do it once.
if (!self.initialScrollDone) {
self.initialScrollDone = YES;
[self.collectionView scrollToItemAtIndexPath:self.myInitialIndexPath
atScrollPosition:UICollectionViewScrollPositionRight animated:NO];
}
}
迅速:
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
if (!self.initialScrollDone) {
self.initialScrollDone = true
self.testNameCollectionView.scrollToItem(at:selectedIndexPath, at: .centeredHorizontally, animated: true)
}
}
这篇关于UICollectionView自动滚动到IndexPath的单元格的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！