Apple's Round Checkmarks - Where and When are they used?

Question

We are building a cross platform app, and a decision maker on my team (who is an Apple user) wants all of our "Select to delete" checkboxes to be round, "Like Apple's Mail and Messages apps".

I personally find this confusing, I think they look like radio buttons. He disgarees that anyone would confuse round circles for radio buttons.

Apple's HIG about checkboxes doesn't specifically state that checkboxes should be a specific shape Apple's HIG on Checkboxes

Apple's Sample Code shows square checkboxes, but that's not selecting to DELETE an item Apple's TableViewCell Sample Code

Have all iOS devices always used round checkmarks to delete items, or is this a new change?

Where and when does iOS use round checkmarks?

Answer 1

Round buttons are the default and standard in multiple selection of iOS table views, and always have been, as far as I know. You can see this in the second screenshot of the "Buttons" page in Apple's iOS Human Interface Guidelines. Try this Swift sample code that invokes UITableView's default multiple selection mode:

import UIKit

class ViewController: UITableViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.allowsMultipleSelectionDuringEditing = true
        tableView.setEditing(true, animated: false)
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell")
        cell?.textLabel?.text = String(indexPath.row)
        return cell!
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 15
    }
}

The above code produces this interface (taken on the iPhone X iOS 11.3 Simulator):