一个UITableViewCell内UICollectionVIew如何获得与自动布局动力高度

问题描述

我知道，有一个类似question,但我想给我是如何试图做到这一点，因为原来的问题没有给予任何建议更多的提示。结果
我有一个的UITableViewCell 的内容查看的子视图有一个 UICollectionView ，我想有单元格高度在的CollectionView contentSize 的功能表视图细胞是集合视图委托和数据源。结果
该集合视图应该是固定不垂直流动滚动的可能性，它应在的细胞数调整其高度。结果
要做到这一点，我试图用我常用的表视图单元格使用相同的技术。我创建了一个假的电池，并保持对它的引用，则在该方法 - （CGFloat的）的tableView：（UITableView的*）的tableView heightForRowAtIndexPath：（NSIndexPath *）indexPath 我喂与数据单元，它应该显示，然后要求其高度为COM pressed大小。结果
这样的事情：结果

I know that there is a similar question, but I'd like to give more hints about how I tried to achieve that since the original question doesn't give any advice.
I have a UITableViewCell as a subview of the contentView there is a UICollectionView, I'd like to have the cell height in function of the collectionview contentSize, the table view cell is the collection view delegate and datasource.
The collection view should be fixed without scrolling possibilities in a vertical flow and it should adapt its height on the number of cell lines.
To do that I've tried to used the same technique I use with common table view cells. I create a fake cell and keep a reference to it, then in the method - (CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath I feed the cell with the data that it should display and then ask to its height for compressed size.
Something like that:

- (CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    CGSize  size = CGSizeZero;
    NSDictionary * data = self.data[indexPath.row];
    if (data[KEY_CELL_IDENTIFIER] == CellIdentifierPost) {
        NSNumber * cachedHeight = [self.heightCaches objectForKey:[(PostObject*)data[KEY_CELL_DATA] postObjectId]];
        if (cachedHeight) {
            return (CGFloat)[cachedHeight doubleValue];
        }
        [_heightCell configureCellWith:data[KEY_CELL_DATA]];
        size = [_heightCell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
        [self.heightCaches setObject:@(size.height) forKey:[(PostObject*)data[KEY_CELL_DATA] postObjectId]];
    }
    else if (data[KEY_CELL_IDENTIFIER] == CellIdentifierComment){
        size = (CGSize) {
            .width = NSIntegerMax,
            .height = 160.f
        };
    }
    else {
        size = (CGSize) {
            .width = NSIntegerMax,
            .height = 50.f
        };
    }

    return size.height;
}

本方法适用于其他单元确实很好，但不是这一个，结果是一个完全融为一体pressed几乎零高度的细胞。结果
这个问题似乎是由于内细胞放置。即使喂养数据后我强迫集合视图重新加载数据时，它似乎永远叫 -collectionView：cellForItemAtIndexPath：出现这种情况可能是因为仍然没有显示单元。结果
有周围的工作？

This method works really fine for the other cells, but not for this one, the result is a totally compressed cell with almost a zero height.
The problem seems to be due to the inner cells placement. Even if after feeding the data I force the collection view to reload data, it seems to never call the -collectionView:cellForItemAtIndexPath: this happens probably because the cell is still not displayed.
Is there a work around?

推荐答案

我建议你创建一个高度约束你的CollectionView。

I'd recommend you to create a height constraint for your collectionView.

然后，基于细胞的数量，你可以计算的高度它，并在结束时，你更新的约束，并调用 [的CollectionView setNeedsUpdateConstraints]

Then, based on the number of cells, you may calculate the height for it, and, at the end, you update that constraint and call [collectionView setNeedsUpdateConstraints]

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