Removing Array element when user didDeselectRowAt?

Question

I'm trying to remove an item of an array when the user deselects a cell. I understand why my code it's not working, basically, the array might contain 5 elements and if there are 100 cells and the user selected cell 10, trying to deselect it via indexPath.row would crash since the array has only 5 elements. The point is when the user deselect the cell, it should remove the corresponding element from the array. That's what I'm not sure how to do

var transferUsers = [UserModel]()

func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
    if let cell = tableView.cellForRow(at: indexPath) {
        selectedUsersCount -= 1
        if selectedUsersCount == 0 {
            nextButton.isEnabled = false
        }
        cell.accessoryType = .none
        transferUsers.remove(at: indexPath.row)
    }
}

I tried this answer, but I get an error saying:

Cannot invoke 'index' with an argument list of type '(of: UserModel)'

What is the relationship/logic between the index path and the array index supposed to be ? The error simply says that UserModel does not conform to Equatable. — vadian
– vadian, Commented Aug 24, 2018 at 18:32
Actually, there isn't. I just thought about it now when you mentioned it. — Dani
– Dani, Commented Aug 24, 2018 at 18:33
Um...how many rows are you showing? What does your numberOfRows:inSection: method return? More code would be helpful. — BitParser
– BitParser, Commented Aug 24, 2018 at 18:42

BitParser · Accepted Answer · 2018-08-24 18:51:25Z

1

Okay, so I think you are displaying a list of rows, and when a cell is selected, you add the user to the transferUsers array. The issue with this is that you do not store the location of the selected user.

A quick fix for this would be to have a dictionary, which combines the index path with the user.

var transferUsers: [IndexPath: UserModel] = [:]

then, when a user is selected, you do this:

transferUsers[indexPath] = usersArray[indexPath.row]

and when a user is deselected, you do this:

transferUsers.removeValue(forKey: indexPath)

selectedUsersCount could be a property:

var selectedUsersCount: Int {
    return transferUsers.count
}

to get only the list of selected users, since you have a dictionary, you would do it like this:

transferUsers.values

answered Aug 24, 2018 at 18:51

BitParser

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1 Comment

Dani Over a year ago

Thank you for the detailed explanation!

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