Adding properties to UIControls without subclassing

Question

I have embedded UIButtons in my TableViewCells. In order to track which cell the button belongs to, I would like to add an NSIndexPath property to UIButton. I do not want to subclass a UIButton. Is there a way I can do this with categories?

EDIT: I believe the idea of setting tags will not work if I have multiple sections in the table view. Another approach of accessing the button's superview's superview to determine the cell seems more like a hack. Looking for a cleaner way of doing this.

Answer 1

There are several approaches. If you just really need a single number rather than a full index path, you can use setTag:. It's inflexible, but it's readily available.

The next best solution is associative references. These can hang data onto any object, with proper memory management. I usually create a category that adds a property implemented using objc_setAssociatedObject and objc_getAssociatedObject.

Answer 2

You can find out which cell a clicked button was in without having to associate tags or index paths with the buttons, which can get messy when re-using cells. Tags do work with sectioned tables but you have to mess about with numbers, e.g. 10001 is section 1, row 1, so you've got to convert at one end and convert back at the other, too fragile for my liking.

A nicer method is to use UITableView's indexPathForRowAtPoint: method. When your button's action is activated (assuming the target is in your table view controller:

CGPoint point = [sender convertPoint:sender.center toView:self.tableView];
NSIndexPath *path = [self.tableView indexPathForRowAtPoint:point];

sender here is cast to UIButton.