crash while deleting rows from tableview

Question

Hello i am i am deleting rows from tableview and its work fine for me i am successfully removed but after remove i am getting crash and error like below

Error

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

and here i show you my code where i am getting crash

Code

@IBAction func btnDeleteYesTapped(_ sender: UIButton) {
    let preferences = UserDefaults.standard
    let uid = "u_id"
    let acTkn = "acc_tkn"

    let u_ID = preferences.object(forKey: uid)
    let A_Token = preferences.object(forKey: acTkn)

    let params = ["user_id": u_ID!, "access_token": A_Token!,"property_id": propertyID!,"occupants_id": oCCID!]
    print(params)
    Alamofire.request(propertyoccupantsdelete, method: .post, parameters: params).responseJSON
        {
            response in
            print(response)
            let result = response.result.value
            print(response)
            let data = result as! [String : AnyObject]
            let status = data["success"] as! String
            if status == "1"{
                let buttonPosition : CGPoint = (sender as AnyObject).convert((sender as AnyObject).bounds.origin, to: self.tblOccList)
                let indexPath = self.tblOccList.indexPathForRow(at: buttonPosition)! //At Here I am Getting crash 
                self.occuPantsData.remove(at: indexPath.row)
                self.tblOccList.deleteRows(at: [indexPath], with: .fade)
                Toast(text: data["message"] as? String).show()
            }else{
              Toast(text: data["message"] as? String).show()
            }
    }
}

i am not able to understand why i am getting crash can any one please tell me where i am done something wrong

Code For Showing Dialogue

 @objc func handleLongPress(longPressGesture:UILongPressGestureRecognizer) {

        let p = longPressGesture.location(in: self.tblOccList)
        let indexPath = self.tblOccList.indexPathForRow(at: p)

        if indexPath == nil {
            print("Long press on table view, not row.")
        }
        else if (longPressGesture.state == UIGestureRecognizer.State.began) {
            print("Long press on row, at \(indexPath!.row)")
            let id = occuPantsData[indexPath!.row].id
            print(id)
            self.oCCID = id
            self.viewDeletePopUp.isHidden = false
        }

    }

You have lots and lots of force unwraps. Be very careful with those. It makes your app very prone to crashes and failure. Your problem here is that you are for unwrapping the indexPath but it is returning nil. `let indexPath = self.tblOccList.indexPathForRow(at: buttonPosition)!` remove the `!` and `guard` unwrap it or unwrap it conditionally with `if let` — Galo Torres Sevilla, Jan 18 '19 at 09:45
when i print `buttonPosition` i will get result like this (206.5, -63.0) — Vishal Parmar, Jan 18 '19 at 09:46
How are you planning to get an indexPath with a tuple? Thats why its crashing. What do you want to achieve here? — emrepun, Jan 18 '19 at 09:51
if i use guard and is let then not able to delete rows from tableview — Vishal Parmar, Jan 18 '19 at 09:57
You are performing UI operations in an asynchronous block too; that isn't a good idea — Paulw11, Jan 18 '19 at 09:57
@Paulw11 can you please suggest me another way to solve this — Vishal Parmar, Jan 18 '19 at 10:02
What is the context for the code shown? Is it in the tableview or in the cell? You have lots of force unwraps - that is bad. You seem to be using user defaults for storing part of your data model - that is bad. You should handle the button tap in your cell and have it notify the tableview of the tap via a delegation pattern. You should immediately delete the item from your local array and delete the row from your tableview and then dispatch the network update to complete in the background — Paulw11, Jan 18 '19 at 10:05
It is not very robust to use the position on screen to recompute the indexPath. Should better attach a tag to each cell and use it to build the indexPath. — claude31, Jan 18 '19 at 12:37

ZHZ · Accepted Answer · 2019-01-18T11:06:37.673

2

You can define a property to save the selected indexPath before pop up the dialogue.

var selectedIndexPath: IndexPath?

And change this

let indexPath = self.tblOccList.indexPathForRow(at: p)

        if indexPath == nil {
            print("Long press on table view, not row.")
        }

To

self.selectedIndexPath = self.tblOccList.indexPathForRow(at: p)

        if self.indexPath == nil {
            print("Long press on table view, not row.")
        }

Then try changing this

let indexPath = self.tblOccList.indexPathForRow(at: buttonPosition)!

to

guard let indexPath = self.selectedIndexPath else { return }

edited Jan 18 '19 at 11:06

answered Jan 18 '19 at 09:56

ZHZ

2,088
13
16

if i am replacing with your code i am getting error lik this `Cannot convert value of type 'PropertyDetailViewController' to expected argument type 'UITableViewCell'` – Vishal Parmar Jan 18 '19 at 09:58
I am showing popup on tableview cell long press and then i am deleting the row if their any possibility for that this crash in getting – Vishal Parmar Jan 18 '19 at 10:04
no the delete button on popup means on long press of cell i am showing popup for confirm delete and then on yes button i am deleting – Vishal Parmar Jan 18 '19 at 10:06
Updated the answer. Hope that help – ZHZ Jan 18 '19 at 10:11
please check image i am getting success response but still row not removed from tableview and when i run again then data doesn't appear beacuse its deleted – Vishal Parmar Jan 18 '19 at 10:25
Do you saved the clicked cell to selectedCell? – ZHZ Jan 18 '19 at 10:38
where i want to save clicked cell to selected cell not able to understand – Vishal Parmar Jan 18 '19 at 10:43
Can you post the code of showing the popup dialogue? – ZHZ Jan 18 '19 at 10:46
Please check i Updated question – Vishal Parmar Jan 18 '19 at 10:47
Please give me solution if you understand whats the issue – Vishal Parmar Jan 18 '19 at 10:58
`self.indexPath = self.tblOccList.indexPathForRow(at: p) if self.indexPath == nil { print("Long press on table view, not row.") }`in this from where you can get `self.indexPath` – Vishal Parmar Jan 18 '19 at 11:05
The idea is save the clicked row instead of recalculation – ZHZ Jan 18 '19 at 11:08
It’s my pleasure. – ZHZ Jan 18 '19 at 11:17

Abhishek Jadhav · Answer 2 · 2019-01-18T11:06:12.630

Add in tableview cellForRowAt delegate method assign button tag to indexPath.row

     cell.button.tag = indexPath.row 

    @IBAction func btnDeleteYesTapped(sender: UIButton) {
    let preferences = UserDefaults.standard
    let uid = "u_id"
    let acTkn = "acc_tkn"

    let u_ID = preferences.object(forKey: uid)
    let A_Token = preferences.object(forKey: acTkn)

    let params = ["user_id": u_ID!, "access_token": A_Token!,"property_id": propertyID!,"occupants_id": oCCID!]
    print(params)
    Alamofire.request(propertyoccupantsdelete, method: .post, parameters: params).responseJSON
        {
            response in
            print(response)
            let result = response.result.value
            print(response)
            let data = result as! [String : AnyObject]
            let status = data["success"] as! String
            if status == "1"{                
                let indexPath = IndexPath(row: sender.tag, section: 0)
                self.occuPantsData.remove(at: indexPath.row)
                self.tblOccList.reloadData()
                Toast(text: data["message"] as? String).show()
            }else{
              Toast(text: data["message"] as? String).show()
            }
    }
}

this not working its give me crash on same where i am getting — Vishal Parmar, Jan 18 '19 at 10:59
No you can check just two lines you have to add after success and assign indexPath.row to button.tag — Abhishek Jadhav, Jan 18 '19 at 11:06

crash while deleting rows from tableview

2 Answers2