Enable bounce/scroll for UICollectionView while no cells - ios

Question

Due to some purposes(like pull to refresh), I need a UICollectionView can bounce or scroll when there is no cells -- means numberOfItemsInSection: return 0
I have my code like this:
...
UICollectionViewFlowLayout *flowLayout =[[UICollectionViewFlowLayout alloc] init];
flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;
flowLayout.minimumInteritemSpacing = SPLIT_SPACE;
flowLayout.minimumLineSpacing = SPLIT_SPACE;
targetCollection = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height - TABBAR_HEIGHT)
collectionViewLayout:flowLayout];
[targetCollection registerNib:[UINib nibWithNibName:#"DashboardCell" bundle:[NSBundle mainBundle]] forCellWithReuseIdentifier:#"DashboardCell"];
targetCollection.autoresizingMask = UIViewAutoresizingFlexibleHeight;
targetCollection.backgroundColor = [UIColor colorWithHex:#"#EAEAEA"];
targetCollection.contentInset = UIEdgeInsetsMake(0, 0, 20, 0);
targetCollection.alwaysBounceVertical = YES;
...
#pragma mark - UICollectionViewDataSource
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section;
{
return 0;
}
However, when testing, this empty UICollectionView cannot bounce nor scroll. I suspect it is related to empty cell, but I do need to enable the bounce or scroll when no cell.
This is similar to another of my problem:SVPullToRefresh cannot pull on an empty UICollectionView

Answer 1

Do it like this:
self.collectionView.alwaysBounceVertical = YES;
answer by #VNJ at here

Answer 2

Change this setting in your storyboard:

Answer 3

Swift Solution
collectionView.alwaysBounceVertical = true

Answer 4

You can try this:
collectionView.isScrollEnabled = false

Answer 5

- (void)_edgeInsetsToFit {
UIEdgeInsets edgeInsets = self.collectionView.contentInset;
CGSize contentSize = self.collectionView.contentSize;
CGSize size = self.collectionView.bounds.size;
CGFloat heightOffset = (contentSize.height + edgeInsets.top) - size.height;
if (heightOffset < 0) {
edgeInsets.bottom = size.height - (contentSize.height + edgeInsets.top) + 1;
self.collectionView.contentInset = edgeInsets;
} else {
edgeInsets.bottom = 0;
self.collectionView.contentInset = edgeInsets;
}
}
I called that method after layoutSubviews
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
_STAssetViewController *weakSelf = self;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.01 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[weakSelf _edgeInsetsToFit];
});
}
You can try that way