UICollectionView remove whitespace/header iOS11 - ios

Question

I have a UICollection view which looks like this (see two purple and blue borders):
On iOS 10 there is no header/whitespace, but on iOS11 there is. I've tried everything mentioned here: How can I enable/disable section headers in UICollectionView programmatically?
And my code currently looks like this:
- (void) viewDidLoad
{
[super viewDidLoad];
autocompleteLayout = [[SQLProAutocompleteFlowLayout alloc] init];
autocompleteLayout.headerReferenceSize = CGSizeZero;
autocompleteCollectionView = [[UICollectionView alloc] initWithFrame: CGRectZero
collectionViewLayout: autocompleteLayout];
autocompleteCollectionView.insetsLayoutMarginsFromSafeArea = NO;
[self.view addSubview: autocompleteCollectionView];
// removed layout code (leftAnchor, rightAnchor, topAnchor, bottomAnchor).
autocompleteCollectionView.delegate = self;
autocompleteCollectionView.dataSource = self;
// Removed nib register code
self.view.layer.borderColor = [UIColor redColor].CGColor;
self.view.layer.borderWidth = 1;
autocompleteCollectionView.layer.borderColor = [UIColor blueColor].CGColor;
autocompleteCollectionView.layer.borderWidth = 2;
}
- (CGSize) collectionView: (UICollectionView *) collectionView
layout: (UICollectionViewLayout *) collectionViewLayout
referenceSizeForHeaderInSection:(NSInteger)section
{
return CGSizeZero;
}
- (CGSize)collectionView:(UICollectionView *)collectionView
layout:(UICollectionViewLayout *)collectionViewLayout
referenceSizeForFooterInSection:(NSInteger)section
{
return CGSizeZero;
}
And my FlowLayout looks like this:
- (void) setupLayout
{
self.minimumInteritemSpacing = 0;
self.minimumLineSpacing = 0;
self.scrollDirection = UICollectionViewScrollDirectionVertical;
} // End of setupLayout
- (void) prepareLayout
{
[super setItemSize: [self itemSize]];
[super setSectionInset: [self sectionInset]];
self.minimumLineSpacing = 0;
[super prepareLayout];
} // End of prepareLayout
- (CGFloat) itemWidth
{
return self.collectionView.frame.size.width;
}
- (CGSize) itemSize
{
CGSize result = CGSizeMake(self.collectionView.frame.size.width,
rowHeight);
return result;
}
- (void) setItemSize:(CGSize)itemSize
{
self.itemSize = CGSizeMake(self.collectionView.frame.size.width,
rowHeight);
}
- (CGPoint) targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset
{
return CGPointZero;
}
I have also verified that the UICollectionView's contentInset is zero'd out.
What am I missing? Why does my UICollectionView still have whitespace?

Answer 1

In iOS 11, there have been some changes to UIScrollView.
Try setting the contentInsetAdjustmentBehavior property
collectionView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;

Answer 2

Try this:
self.automaticallyAdjustsScrollViewInsets = false
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
return 0;
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
return 0;
}
- (UIEdgeInsets)collectionView:
(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake(-25,0,0,0); // top, left, bottom, right
}