Detect Distance between UITableView Section Headers - iphone

Question

In a plain UITableView with custom UIView's as section headers, is there a way to calculate:
When one of the Section is on the top, the distance between that section and the next one that would come?
I am expecting to calculate this here:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView

Answer 1

You can find the number of rows in that section by calling the tableView:numberOfRowsInSection: method from the UITableViewDataSourceDelegate protocol. You can get the height for each row in the section with the tableView:heightForRowAtIndexPath: method from the UITableViewDelegate protocol. Add up the height for all the rows and you have the distance you want.
Your code would look something like this, assuming you have a reference to the tableview and the section.
float totalHeight = 0;
for (int i = 0; i < [tableViewDataSourceDelegate
tableView:tableView
numberOfRowsInSection:section]; i ++) {
totalHeight += [tableViewDelegate
tableView:tableView
heightForRowAtIndexPath:[NSIndexPath
indexPathForRow:i
inSection:section]];
}
Haven't had a chance to test this code, but it Should Work[tm].
Edit
This will only work if the header is at the top.

Answer 2

(assuming all rows are same height)
NSIndexPath *topCellIndexPath = [tableView indexPathsForVisibleRows][0];
UITableViewCell *topCell = [tableView cellForRowAtIndexPath: topCellIndexPath];
CGFloat distanceToNextSection = [tableView convertRect: [topCell frame] fromView: topCell.superview].origin.y - tableView.contentOffset.y + ([self tableView: tableView numberOfRowsInSection: topCellIndexPath.section] - topCellIndexPath.row)*tableView.rowHeight

Answer 3

I was able to solve this by doing the following:
Before creating an section header, check if you have the section header for a given section. If you do return it from the NSMutableArray. If not keep going.
When you create the section header, keep a reference to it in a NSMutableArray.
When you scroll in:
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
Do the following:
// Get the toppest section
NSUInteger sectionNumber = [[self.tableView indexPathForCell:[[self.tableView visibleCells] objectAtIndex: 0]] section];
// Get a reference to it
SFBasicSectionHeader *topHeader = [arrayOfWeakHeaders objectAtIndex:sectionNumber];
SFBasicSectionHeader *bellowHeader;
// Check if it's Ok to get the bellow header
if (sectionNumber+1<[arrayOfWeakHeaders count] && [arrayOfWeakHeaders objectAtIndex:sectionNumber +1])
{
bellowHeader = [arrayOfWeakHeaders objectAtIndex:sectionNumber+1];
}
The difference between both will be:
CGFloat differenceBetweenTopAndBellowSection = bellowHeader.frame.origin.y - topHeader.frame.size.height - self.tableView.contentOffset.y;
Done.