What Is the Meaning of the "No Index Path for Table Cell Being Reused" Message in iOS 6/7

What is the meaning of the no index path for table cell being reused message in iOS 6/7?

I started to get this error showing up in the log from iOS 7 beta 5 onwards, including in the iOS 7 GM/Release build, whilst never having had it happen in my app in iOS 6 or the earlier iOS 7 betas. After a lot of experimenting I found the cause:

I was using UITableViewCell objects for my section header views and returning them in tableView:viewForHeaderInSection:. This appears to be common practice, especially since iOS 5 when it became easy to design a section header view as a prototype table view cell in a StoryBoard with Interface Builder.

When I changed my app to use just regular UIView subclasses for my section header views, the errors went away and, more importantly, my table view stopped randomly deleting section headers!

It would appear that (since iOS 7 beta 5) UITableView is internally maintaining a mapping of all the UITableViewCell objects in its view hierarchy and their respective index paths. Since a section header (or a table view header of footer) doesn't have an index path, if you use a UITableViewCell object for these views, the table view will get confused when it finds a UITableViewCell for which it doesn't have an index path, resulting in the "no index path for table cell being reused" error and, if you're unlucky, display glitches in your table view:

UPDATE: if you have access to the Apple Dev Forums, here's the thread about it (which I started): https://devforums.apple.com/message/882042#882042

As suggested in that thread, if you don't want to re-factor much, you can create a UIView wrapper around your UITableViewCell and return that as the section header view.

UIView *view = [[UIView alloc] initWithFrame:[cell frame]];
[view addSubview:cell];

return view;

Note however that this "wrapper" UIView approach will not play well with AutoLayout and device rotation, so I suggest that you use a UIView subclass for header and footer cells, not a UITableViewCell subclass as explained in the main part of the answer.

No index path for table cell being reused

I worked this out after a few days. In my custom cell I had a textView, when I was adding it to the contentView I was doing this:

[self.cellTextView setClearsOnInsertion:YES];

This was the cause of the issue; incase anyone else has a similar problem.

Happy coding :-)

no index path for table cell being reused leading to app crash

You can try to disable touches on the webView and intercept the touches in the didSelectRow.

Also instead of [tableView reloadData] try using:

[tableView beginUpdates];
[tableView endUpdates];

It almost always works better for collapsing tableviews.

Custom table cells iOS 6

See the documentation of dequeueReusableCellWithIdentifier: for iOS 6:

If you registered a class for the specified identifier and a new cell
must be created, this method initializes the cell by calling its
initWithStyle:reuseIdentifier: method.

You have registered a class with

[SettingsTable registerClass:[TextFieldTableCell class] forCellReuseIdentifier:@"textFieldCell"];

and therefore dequeueReusableCellWithIdentifier: never returns nil.

You should create the subviews of the table view cell in the initWithStyle:reuseIdentifier: method of your TextFieldTableCell class, for example:

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        self.textField = [[UITextField alloc] initWithFrame:CGRectMake(10, 0, 295, 43)];
        self.textField.autoresizingMask = UIViewAutoresizingFlexibleWidth;
        self.textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
        [self.contentView addSubview:self.textField];
    }
    return self;
}

An alternative is to implement prepareForReuse in your TextFieldTableCell class to "clean up" the cell content for reuse.

Is changing the table height by changing its contrains good practice?

Things I look out for to avoid the problems you are in,

• Try avoiding any constants or values for dimensions as much as possible.
• Use constraints and try defining it in exactly one place ( StoryBoard, Xib, or in code).

As its height to be determined by its content attaching to screen edge won't work.

As for your queries,

• Try checking if any conflicting constraints appear on the storyboard and code. Like if the whole tableview is defined in the storyboard, why not tableView.rowHeight = 50 remains there as well.
• While deleting, tableView.deleteRows() have .autometic animation. As per doc, case automatic = 100 // available in iOS 5.0. chooses an appropriate animation style for you. Let's set that to .none.

Kindly check if the reviewed snippet below works.

   var data = [1,2,3,4,5,6,7,8,9,10]

    @IBOutlet weak var tableView: UITableView!
    @IBOutlet weak var tableViewHeight: NSLayoutConstraint!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.rowHeight = 50
        tableViewHeight.constant = CGFloat(data.count) * tableView.rowHeight
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        self.tableViewHeight.constant = CGFloat(self.data.count) * self.tableView.rowHeight
        return data.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = "\(data[indexPath.row])"
        return cell
    }
    
    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        // I think this is causing the problem. 
         if editingStyle == .delete {
            data.remove(at: indexPath.row)
            // use no animation
            tableView.deleteRows(at: [indexPath], with: .none)
            // wont update the constraint here.
            // self.tableViewHeight.constant = CGFloat(self.data.count) * self.tableView.rowHeight
        }
    }
    
    override func setEditing(_ editing: Bool, animated: Bool) {
        super.setEditing(!isEditing, animated: true)
        tableView.setEditing(!tableView.isEditing, animated: true)
    }
}

Also check these as well if haven't already,

• Dynamic UITableView height
• Change UITableView height dynamically

Use a UITableViewCell as tableHeaderView

Not sure how you're setting up your custom cell, but if it has a nib associated with it, you can do this:

HeaderUserLoggedOutCell *userLoggedOutCell = [[[NSBundle mainBundle] loadNibNamed:@"HeaderUserLoggedOutCell" owner:self options:nil] objectAtIndex:0];
// customize your cell in whatever way you need to
self.menuTableView.tableHeaderView = userLoggedOutCell.contentView;

No need to add your custom cell to a separate UIView.

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