Lesson 9 - iOS ToDo app in Swift - Filling in and serialization

In the previous lesson, Creating an iOS ToDo app storing data, we started building a ToDo app.

For today's iOS tutorial, I promised to finish marking tasks as completed and saving data.

Marking tasks as completed

Let's program marking tasks as completed first. We've already prepared a method which is called when the user selects a TableView row. We'll use the accessoryType cell property and set it to .checkmark or .none when the row is selected:

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    if let selectedCell = tableView.cellForRow(at: indexPath) {
        if selectedCell.accessoryType == .checkmark {
            selectedCell.accessoryType = .none
        } else {
            selectedCell.accessoryType = .checkmark
        }
    }
}

If we now select a row, it'll be marked as completed or uncompleted. That's because we set the accessoryType to .none if it's already set to .checkmark.

Bug hunt

It looks like we're done. However, there's a very essential error

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