通过从阵列崩溃中删除项目并出现致命错误来删除tableView中的项目：索引超出范围

Question

I am trying to remove an item from a public static array that is been shown in a tableview. The deletion is occuring in a different viewcontroller and when I try to enter that view controller the app crashes with the error of 'Index out of range'

this is where i delete the Item

func removeItem (info:Dictionary<String, Any>){
    let stringKey = info[KEYS.stringKey] as! String
    for var i in 0 ..< ItemsViewController.itemVideosList.count {

        let current = ItemsViewController.itemVideosList[i]
        let currentStringKey = current[KEYS.stringKey] as! String

        if stringKey == currentStringKey {

            ItemsViewController.itemVideosList.remove(at: i)
            return
        }
    }

I call this method on a button click here:

@IBAction func FavoriteAction(_ sender: Any) {


    if Flag {
        removeFromFavorite(info: songInfo)
        Flag = false
        }
    else {
        ItemsViewController.itemVideosList.insert(songInfo, at: 0)
        favFlag = true
    }
}

I am populating the table view in 'ItemsViewController' viewDidLoad with this method

func loadItems() {
    DispatchQueue.main.async {
        self.itemsTableView.reloadData()
    }
}

thanks

Answer 1

You are trying to loop through when deleting. This leads to ItemsViewController.itemVideosList.count being invalid after your deletion.

1. You can solve your problem simply by adding a break instead of a return

    if stringKey == currentStringKey { ItemsViewController.itemVideosList.remove(at: i) return } 

2. More importantly, you should not modify a collection while iterating it. This leads to undesired side effects. It's better to just store the indexToDelete and then delete it outside of loop.

    func removeItem (info:Dictionary<String, Any>){ let indexToRemove = -1 let stringKey = info[KEYS.stringKey] as! String for var i in 0 ..< ItemsViewController.itemVideosList.count { let current = ItemsViewController.itemVideosList[i] let currentStringKey = current[KEYS.stringKey] as! String if stringKey == currentStringKey { indexToDelete = i break } } ItemsViewController.itemVideosList.remove(at: indexToDelete) } 

Note:

You could make your iteration cleaner using higher-order functions like so:

var list = ["a", "b", "c"]

let index = list.index { (str) -> Bool in
    if str == "b" {
        return true
    }
    return false
}