UICollectionView水平分页未居中 [英] UICollectionView Horizontal Paging not centered

问题描述

我有一个水平滚动的collectionView，每个单元格的大小与视图的大小相同.当我浏览collectionView时，它不是按单元显示的.单元格不在屏幕中央.我已经尝试了很多方法来修复它，但是没有任何运气. 这是问题的视频: https://www.youtube.com/watch?v=tXsxWelk16w 有什么想法吗?

I have a horizontal scrolling collectionView with each cell the size of the view. When I page through the collectionView it doesn't page by cell. The cells aren't in the center of the screen. I've tried a bunch of things to try to fix it and haven't had any luck. Here's a video of the problem: https://www.youtube.com/watch?v=tXsxWelk16w Any ideas?

推荐答案

删除项目之间的空格.对于水平滚动收集视图，请将最小行距设置为0.您可以使用界面生成器或UICollectionViewDelegateFlowLayout协议的方法来完成此操作:

Remove spaces between items. For horizontal scrolling collection view set minimum line spacing to 0. You can do this with interface builder or with method of UICollectionViewDelegateFlowLayout protocol:

- (CGFloat)collectionView:(UICollectionView *)collectionView 
                   layout:(UICollectionViewLayout *)collectionViewLayout 
        minimumLineSpacingForSectionAtIndex:(NSInteger)section {
    return 0;    
}

另一种方法是使单元格的宽度小于collectionView的宽度，以获取项目之间的水平间距.然后添加带有左右插图的部分插图，这些插图等于项目之间水平空间的一半.例如，您的最小行距是10:

Another way is making your cell's width less than collectionView's width for a value of horizontal space between items. Then add section insets with left and right insets that equal a half of horizontal space between items. For example, your minimum line spacing is 10:

- (CGFloat)collectionView:(UICollectionView *)collectionView
                   layout:(UICollectionViewLayout *)collectionViewLayout
        minimumLineSpacingForSectionAtIndex:(NSInteger)section {
    return 10;
}

- (CGSize)collectionView:(UICollectionView *)collectionView 
                  layout:(UICollectionViewLayout *)collectionViewLayout 
  sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    return CGSizeMake(collectionView.frame.size.width - 10, collectionView.frame.size.height);
}

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView 
                        layout:(UICollectionViewLayout *)collectionViewLayout 
        insetForSectionAtIndex:(NSInteger)section {
    return UIEdgeInsetsMake(0, 5, 0, 5);
}

第三种方式:在scrollViewDidEndDecelerating:方法中操作collectionView滚动:

And third way: manipulate collectionView scroll in scrollViewDidEndDecelerating: method:

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    if (scrollView == self.collectionView) {
        CGPoint currentCellOffset = self.collectionView.contentOffset;
        currentCellOffset.x += self.collectionView.frame.size.width / 2;
        NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:currentCellOffset];
        [self.collectionView scrollToItemAtIndexPath:indexPath
                                    atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally
                                            animated:YES];
    }
}

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