NSInternalInconsistencyException updating Tableview

Question

I implemented a tableView to make rows collapsing and expanding; this is my class (I followed this tutorial):

import UIKit
import ChameleonFramework

class AllTeamChantsController: UIViewController, UITableViewDataSource, UITableViewDelegate
{
    var ponte: String?
    var sections: [Section]!

    @IBOutlet weak var tableView: UITableView!

    override func viewDidLoad()
    {
        super.viewDidLoad()

        if let stringaPonte = ponte
        {
            title = stringaPonte
        }

        sections = [Section(name: "Derby", items: ["coro", "coro", "coro", "coro"]),
                    Section(name: "Personagi", items: ["coro", "coro", "coro", "coro"]),
                    Section(name: "Cori", items: ["coro", "coro", "coro", "coro"])]
    }

    override func didReceiveMemoryWarning()
    {
        super.didReceiveMemoryWarning()
    }

    func numberOfSections(in tableView: UITableView) -> Int
    {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
    {
        var count = sections.count

        for section in sections
        {
            count += section.items.count
        }

        return count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
    {
        let section = getSectionIndex(indexPath.row)
        let row = getRowIndex(indexPath.row)

        if row == 0
        {
            let cell = tableView.dequeueReusableCell(withIdentifier: "header") as! AllTeamChantsHeader
            cell.titleLabel.text = sections[section].name
            cell.toogleButton.tag = section
            cell.toogleButton.setTitle(sections[section].collapsed! ? "+" : "-", for: UIControlState())
            cell.toogleButton.addTarget(self, action: #selector(AllTeamChantsController.toggleCollapse), for: .touchUpInside)

            return cell
        }
        else
        {
            let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as UITableViewCell!
            cell?.textLabel?.text = sections[section].items[row - 1]

            return cell!
        }
    }


    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat
    {
        let section = getSectionIndex((indexPath as NSIndexPath).row)
        let row = getRowIndex((indexPath as NSIndexPath).row)

        if row == 0
        {
            return 50.0
        }

        return sections[section].collapsed! ? 0 : 44.0
    }

    // MARK: - Event Handlers

    func toggleCollapse(_ sender: UIButton) {
        let section = sender.tag
        let collapsed = sections[section].collapsed

        // Toggle collapse
        sections[section].collapsed = collapsed!

        let indices = getHeaderIndices()

        let start = indices[section]
        let end = start + sections[section].items.count

        tableView.beginUpdates()
        for i in start ..< end + 1 {
            tableView.reloadRows(at: [IndexPath(row: i, section: 1)], with: .automatic)
        }
        tableView.endUpdates()
    }

    // MARK: - Helper Functions

    func getSectionIndex(_ row: NSInteger) -> Int {
        let indices = getHeaderIndices()

        for i in 0..<indices.count {
            if i == indices.count - 1 || row < indices[i + 1] {
                return i
            }
        }

        return -1
    }

    func getRowIndex(_ row: NSInteger) -> Int {
        var index = row
        let indices = getHeaderIndices()

        for i in 0..<indices.count {
            if i == indices.count - 1 || row < indices[i + 1] {
                index -= indices[i]
                break
            }
        }

        return index
    }

    func getHeaderIndices() -> [Int] {
        var index = 0
        var indices: [Int] = []

        for section in sections {
            indices.append(index)
            index += section.items.count + 1
        }

        return indices
    }
}

The problem is that when I touch the toggle button my app crashes and Xcode send me this message in console

"Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'attempt to delete row X from section 1, but there are only 1 sections before the update".

Could anyone help me to solve this problem? I just tried to look around numberOfRowsInSection and toggleCollapse methods, but I didn't find any issue.

Answer 1

This is the mistake:

for i in start ..< end + 1 {
  tableView.reloadRows(at: [IndexPath(row: i, section: 1)], with: .automatic)
}

obviously if I delete the first section I have to reload indexPath at section 0 not 1! this solve the crash!