CODEWITHSUNDEEP
iosswiftuitableviewautolayout
user339946
user339946

Reputation: 6119

Reusing cells with dynamic layout content at runtime

I have a type of UITableViewCell that lets the user add/remove as many UITextViews as they want at run time.

I'm running into issues when trying to reuse/dequeue cells of that type, as sometimes the tableview cells just start overlapping when you scroll up and down. When I dequeue/return the cell, I'm running a setup method (which initiates a teardown method internally first to remove all the previous views), and uses the model to setup/restore all the necessary views and layout constraints.

 if let cell = tableView.dequeueReusableCell(withIdentifier: "MultipleContentCell", for: indexPath) as? MultipleChoiceTableViewCell {
                    cell.setupCellWithModel(model: model)
                    cell.setNeedsUpdateConstraints()
                    cell.updateConstraintsIfNeeded()
                    cell.delegate = self

                    return cell
                }

I can't really figure out why that cells sometimes overlap in the tableview, but I'm guessing it has to do with the layout being recreated on the fly. I'm considering not reusing these types of cells and just storing them in a list.

My question is: are reusable cells always suppose to have the same general UIView layout, and only the content changes? Am I not supposed to use reuse these types of cells? Or has someone experienced this before?

Thanks

Upvotes: 0

Views: 993

Answers (2)

Duncan C
Duncan C

Reputation: 131436

In general, yes. You want the physical layout of your cells to be static, and only vary the contents when you recycle them. If you add views to your cells in cellForRow(at:) then the burden is on you to manage the extra fields to avoid duplicate views.

Your case where you add a variable number of views to a table view cell based on user interaction is an odd case where you might need to add and remove cells on the fly.

One way to handle this would be to put all of your text fields in a container view, add an outlet to that container view, and then simply use code like this in your prepareForReuse or cellForRowAt function:

containerView.subviews.forEach { $0.removeFromSuperview() }

Upvotes: 0

jLaszczewski
jLaszczewski

Reputation: 99

The UITextView are created each time you dequeue cell and never delete. To repair that use function prepareForReuse(). You have to define, what your cell should do before dequeue in MultipleChoiceTableViewCell. For example:

override func prepareForReuse() {
    super.prepareForReuse()

    for view in speciesName.subviews {
        if view is UITableView {
            view.removeFromSuperview()
        }
    }
}

I added similar question few days ago:

Cells in UITableView overlapping. Many cells in one place

If you have some question, I can try to help you more tomorrow. Cheers!

Upvotes: 1

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