Correct way to setting a tag to all cells in TableView

Question

I\'m using a button inside a tableView in which I get the indexPath.row when is pressed. But it only works fine when the cells can be displayed in

Answer 1

I agree with @matt that this is not a good use of tags, but disagree with him slightly about the solution. Instead of walking up the button's superviews until you find a cell, I prefer to get the button's origin, convert it to table view coordinates, and then ask the table view for the indexPath of the cell that contains those coordinates.

I wish Apple would add a function indexPathForView(_:) to UITableView. It's a common need, and easy to implement. To that end, here is a simple extension to UITableView that lets you ask a table view for the indexPath of any view that lies inside one of the tableView's cells.

Below is the key code for the extension, in both Objective-C and Swift. There is a working project on GitHub called TableViewExtension-Obj-C that illustrates the uses of the table view extension below.

EDIT

In Objective-C:

Header file UITableView_indexPathForView.h:

#import 
@interface UIView (indexPathForView)
- (NSIndexPath *) indexPathForView: (UIView *) view;
@end

UITableView_indexPathForView.m file:

#import "UITableView_indexPathForView.h"

@implementation UITableView (UITableView_indexPathForView)

- (NSIndexPath *) indexPathForView: (UIView *) view {
  CGPoint origin = view.bounds.origin;
  CGPoint viewOrigin = [self convertPoint: origin fromView: view];
  return [self indexPathForRowAtPoint: viewOrigin];
}

And the IBAction on the button:

- (void) buttonTapped: (UIButton *) sender {
  NSIndexPath *indexPath = [self.tableView indexPathForView: sender];
  NSLog(@"Button tapped at indexpPath [%ld-%ld]",
        (long)indexPath.section,
        (long)indexPath.row);
}

In Swift:

import UIKit

public extension UITableView {
  func indexPathForView(_ view: UIView) -> IndexPath? {
    let origin = view.bounds.origin
    let viewOrigin = self.convert(origin, from: view)
    let indexPath = self.indexPathForRow(at: viewOrigin)
    return indexPath
  }
}

I added this as a file "UITableView+indexPathForView" to a test project to make sure I got everything correct. Then in the IBAction for a button that is inside a cell:

func buttonTapped(_ button: UIButton) {
  let indexPath = self.tableView.indexPathForView(button)
  print("Button tapped at indexPath \(indexPath)")
}

I made the extension work on any UIView, not just buttons, so that it's more general-purpose.

The nice thing about this extension is that you can drop it into any project and it adds the new indexPathForView(_:) function to all your table views without having do change your other code at all.