Swift - How to reorder all the cells in the tableview by its attribute？

Question

I have a tableView with cells. There are also items whose type are Dialog . Here is the cellForRow At function:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {


    let cell = tableView.dequeueReusableCell(withIdentifier: "DialogCell", for: indexPath) as! DialogCell

    var item: Dialog

    item = items[indexPath.row]

    ......

    return cell
}

Now, what I'd like to do is to order these cells with the number of item.getLastMessageCreateAt() , which returns an Int number. What should I do?

Up to now, here is what I have tried already:

func getAllCells() -> [UITableViewCell] {

    var cells = [UITableViewCell]()
    for i in 0...tableView.numberOfSections-1
    {
        for j in 0...tableView.numberOfRows(inSection: i)-1
        {
            if let cell = tableView.cellForRow(at: NSIndexPath(row: j, section: i) as IndexPath) {

                cells.append(cell)
            }

        }
    }
    return cells
}

func reorderCells() {

    var lastMessageAgoArray = [Int]()
    for item in self.items {
        lastMessageAgoArray.append(item.getLastMessageCreateAt())
    }
    let timeAgoInNumArrayBigToSmall: [Int] = lastMessageAgoArray.sorted { $0 > $1 }

    let cells = self.getAllCells()

    for cell in cells {
        let row = self.tableView.indexPath(for: cell)?.row
        if ( lastMessageAgoArray[row!] != timeAgoInNumArrayBigToSmall[row!] ) {
            if let index = timeAgoInNumArrayBigToSmall.index(of: lastMessageAgoArray[row!]) {
                self.tableView.moveRow(at: IndexPath(row: row!, section: 0), to: IndexPath(row: index, section: 0))
            }
            self.tableView.reloadData()
        }
    }

}

I have tried to run this, but I got nil of the row at the end of this line:

let row = self.tableView.indexPath(for: cell)?.row

So what should I do to order these cells?

Thank you very much!

Answer 1

Set items as:

items = myItemList.sorted { $0.getLastMessageCreateAt() > $1.getLastMessageCreateAt() } 

And you can keep the code inside func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) the same, and remove getAllCells() as well as reorderCells() .

You don't want to sort the cells themselves as they are reused by the tableview depending on which cells are currently visible on the screen.