尝试将第 3 行插入第 0 节，但更新后第 0 节中只有 3 行

Question

There is strange thing with may tableView

I have

In my delegate I have

var editingIndexPath: IndexPath?

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        if let editingIndexPath = editingIndexPath {
            return datasource.count + 1
        } else {
            return datasource.count
        }

    }

In my didSelect I have

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

            if let oldEditingIndexPath = editingIndexPath {
                    self.editingIndexPath = nil
                    tableView.reloadData()
                    self.editingIndexPath = IndexPath(row: indexPath.row + 1, section: 0)
                    tableView.insertRows(at: [self.editingIndexPath!], with: .top)
            } else {
                editingIndexPath = IndexPath(row: indexPath.row + 1, section: 0)
                if let editingIndexPath = editingIndexPath {
                    tableView.insertRows(at: [editingIndexPath], with: .top)
                }
            }
    }

The problem that it crashes after tableView.reloadData() with error

'attempt to insert row 3 into section 0, but there are only 3 rows in section 0 after the update'

I dont get it. TableView has exactly same number of rows it needs to perform insert. I set property to nil and then reload table, by this action I reduce table's rows number to two. Then I again set editingIndexPath to not nil value signaling delegate method that it should use count + 1. But it fails same way.

And what is also interesting that the same code but without reload before never fails

            editingIndexPath = IndexPath(row: indexPath.row + 1, section: 0)
            if let editingIndexPath = editingIndexPath {
                tableView.insertRows(at: [editingIndexPath], with: .top)
            }

What's happening here ?

Answer 1

Table view has numberOfRowsInSection 3 for section 0(Row1, Row1, Row3). On trying to insert Row4, which exceeds numberOfRowsInSection count, the above-mentioned error is thrown

This may work better( Note: Clueless of logic intended)

  func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
     // better to check with datasource array elements count
     if indexPath.row + 1 < tableView.numberOfRows(inSection: indexPath.section) {
          self.editingIndexPath = IndexPath(row: indexPath.row + 1, section: 0)
          tableView.insertRows(at: [self.editingIndexPath!], with: .top)
     } 
  }