UITableView Find Location of Section header? - iphone

Question

I am trying to find out the location of a swipeGesture when swiped on a tableview.
In the swipe action, I've seen many people do this:
CGPoint location = [recognizer locationInView:tableView];
NSIndexPath* indexPath = [tableView indexPathForRowAtPoint:location];
UITableViewCell* cell = [tableView cellForRowAtIndexPath:indexPath];
But my tableView is made up of section headers that have no cells in them. Because of that, the index path method returns nil. Is there any way to find the location of the Section header? They don't have this method, but something like indexPathForSectionAtPoint: would be the kind of thing I'm looking for.
If anybody knows how to do this, it would be greatly appreciated.
Thanks,

Answer 1

You already have the location and the indexPath.
Now, to get the cell (and its data) you use indexPath.row, as in your example.
To get the section (with or without cell) you use indexPath.section.
If there is no row beneath the point location indexPathForRowAtPoint: will return nil, so that is expected behavior.
Section headings are not really meant to be areas of the view for interaction. Rather they are headings. The UITableView is designed to respond to interaction with its rows.
Maybe one way to fix this is to change your data structure so that the content you display in your section headings really lives in table view rows.
Another approach would be to use the UIView of the section header and have it respond to the swipe gesture. (Make sure you pass the gesture on to the table view with super.)

Answer 2

Ended up doing something similar, but with a tap gesture on the table section header (instead of swipe).
There are probably more elegant ways to do this, but I basically convert the gesture's view to the tableView coordinate space. Then I iterate over each section header's CGRect to see if it intersects with the gesture origin.
func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let cell = tableView.dequeueReusableCellWithIdentifier("header") as! HeaderCell
let tapHeader = UITapGestureRecognizer(target: self, action: "tappedOnHeader:")
tapHeader.delegate = self
tapHeader.numberOfTapsRequired = 1
tapHeader.numberOfTouchesRequired = 1
cell.contentView.addGestureRecognizer(tapHeader)
return cell
}
func tappedOnHeader(gesture:UIGestureRecognizer){
if let cellContentView = gesture.view {
let tappedPoint = cellContentView.convertPoint(cellContentView.bounds.origin, toView: tableView)
for i in 0..<tableView.numberOfSections {
let sectionHeaderArea = tableView.rectForHeaderInSection(i)
if CGRectContainsPoint(sectionHeaderArea, tappedPoint) {
print("tapped on section header:: \(i)")
}
}
}
}
Created a git branch on another tutorial project as a working example:
https://github.com/ThornTechPublic/HorizontalScrollingCollectionView/tree/sectionHeaderTap

Answer 3

//Sublcass a header footer view and in .h file declare this protocol
#protocol MyProtocol <NSObject>
-(void)userTappedView:(UITableViewHeaderFooterView *)view atPoint:(CGPoint)point;
#end
//in same .h file add this
#property (weak, nonatomic) id <MyProtocol> delegate;
//In same subclass .m file do this
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesEnded:touches withEvent:event];
UITouch *touch = [[event allTouches] anyObject];
CGPoint point = [touch locationInView:self];
[self.delegate userTappedView:self atPoint:point];
}
//In controller containing tableview, conform to 'MyProtocol' like this
-(void)userTappedView:(UITableViewHeaderFooterView *)view atPoint:(CGPoint)point {
NSNumber *value = [self sectionForUserSelectionInTableView:self.tableView
atTouchLocation:point
inHeaderFooterView:view];
if (!value) {
return;
}
NSUInteger tappedSection = value.integerValue;
}
-(NSNumber *)sectionForUserSelectionInTableView:(UITableView *)tableView
atTouchLocation:(CGPoint)location
inHeaderFooterView:(UITableViewHeaderFooterView *)view {
CGPoint point = [tableView convertPoint:location
fromView:view];
for (NSInteger i = 0; i < [tableView numberOfSections]; i++) {
CGRect rect = [tableView rectForHeaderInSection:i];
if (CGRectContainsPoint(rect, point)) {
return #(i);
}
}
return nil;
}