iOS Swift - TableView Delete Row Bug

Question

The error: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'

Looking at many related posts, I still cannot find the answer.

Here are the relevant code snippets (does not contain all of the code):

var todoItems : [Assignment] = []
var sections = Dictionary<String, Array<Assignment>>()
var sortedSections = [String]()

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
    if editingStyle == UITableViewCellEditingStyle.Delete {
        var tableSection = sections[sortedSections[indexPath.section]]
        tableSection!.removeAtIndex(indexPath.row)
        tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)
    }

}


override func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    return sortedSections[section]
}

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

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

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return sections.count
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return sections[sortedSections[section]]!.count
}

Thanks for the help!

Vlad · Accepted Answer · 2016-01-16 06:39:12Z

1

You deleted element in array but update of Dictionary with sections is missed :(

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
    if editingStyle == UITableViewCellEditingStyle.Delete {
        var tableSection = sections[sortedSections[indexPath.section]]
        tableSection!.removeAtIndex(indexPath.row)

        //add this line
        sections[sortedSections[indexPath.section]] = tableSection

        tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)
}

}

answered Jan 16, 2016 at 6:39

Vlad

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4 Comments

dannybess Over a year ago

How would I go about deleting the section as well, if the item was the only one in the section?

Vlad Over a year ago

Content of cells in your table are defined here var sections = Dictionary<String, Array<Assignment>>() , but you delete row only tableSection (var tableSection = tableSection[sortedSections[indexPath.section]]) but Dictionary tableSection was not updated <- this is the resaon of error

dannybess Over a year ago

I also have Sections (headers) above each cell. However, if I delete only the cell, the Section Header stays. I am wondering how to delete that as well?

Vlad Over a year ago

You have to add check if section has any cell. If there is no any cell in section - you have to remove sectino too.

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