UICollectionView wrapper view frame update - ios

Question

I have a collection view wrap by UIView, the collection view has same bounds with wrapper view. And collection view data source will be changed, so the wrapper view bounds also be changed. I have implement the wrapper view intrinsicContentSize method with collectionView.collectionViewLayout.collectionViewContentSize, and the collection view layout is subclass of UICollectionViewFlowLayout, the cell of the UICollectionView has also implement method intrinsicContentSize, but the wrapper view did not update frame with collection view content size. collectionViewContentSize is always CGRectZero.
I have tried
[self.layout invalidateLayout];
[self.collectionView reloadData];
[self.collectionView layoutIfNeeded];
but did not work,
What should I do to update the wrapper view frame with collectionView.collectionViewLayout.collectionViewContentSize.
There is some code below:
ZXCollectionViewWrapperView *wrapperView = [[ZXCollectionViewWrapperView alloc] init];
[self.view addSubview:wrapperView];
[wrapperView mas_makeConstraints:^(MASConstraintMaker *make) {
make.center.equalTo(self.view);
}];
self.wrapperView = wrapperView;
/// wrapper view size
- (CGSize)intrinsicContentSize {
return self.collectionView.collectionViewLayout.collectionViewContentSize;
}
ZXCollectionViewAlignedLayout *layout = [[ZXCollectionViewAlignedLayout alloc] init];
self.layout = layout;
ZXCollectionView *collectionView = [[ZXCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
collectionView.dataSource = self;
collectionView.delegate = self;
collectionView.backgroundColor = [UIColor lightGrayColor];
[self addSubview:collectionView];
[collectionView mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(self);
}];
self.collectionView = collectionView;
[self.collectionView zx_registerCellClass:[ZXCommendCell class]];
self.dataSource = dataSource;
[self.collectionView reloadData];
[self.collectionView layoutIfNeeded];

Answer 1

As you are using autolayout, you should create a height constraint for wrapper view. Then you can change the constant of that constraint to equal collection view content size, like this:
heightConstraint = make.height.equalTo(200) // initial height
then you can use KVO to observe collection view content size to change and set
heightConstraint.constant = collectionView.contentSize.height
you can refer to this for observing contentSize: observing contentSize (CGSize) with KVO in swift