Unexpectedly found nil while unwrapping an Optional value swift

Question

I'm getting an error message "Unexpectedly found nil while unwrapping an Optional" from Swift, with the below class. The error occurs on the line:

(cell.contentView.viewWithTag(1) as UILabel).text = object["firstName"] as? String

I have a custom cell class with 2 UILabels tagged 1 and 2, the outlets are set

    import UIKit
    import Foundation

    class dictionaryTableViewController: UIViewController,       UITableViewDelegate, UITableViewDataSource{

    var objects = NSMutableArray()
    var dataArray = [["firstName":"Debasis","lastName":"Das","email":"[email protected]"],["firstName":"John","lastName":"Doe","email":"[email protected]"],["firstName":"Jane","lastName":"Doe","email":"[email protected]"],["firstName":"Mary","lastName":"Jane","email":"[email protected]"]]

    @IBOutlet
    var tableView: UITableView!

    var items: [String] = ["We", "Heart", "Swift"]

    override func viewDidLoad() {
        super.viewDidLoad()
        self.tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: "MyCell")
    }

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


    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dataArray.count;//self.items.count;
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        //var cell:UITableViewCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as UITableViewCell
        //cell.textLabel?.text = self.items[indexPath.row]
        //return cell
        let cell = tableView.dequeueReusableCellWithIdentifier("MyCell", forIndexPath: indexPath) as UITableViewCell
        let object = dataArray[indexPath.row] as NSDictionary
        (cell.contentView.viewWithTag(1) as UILabel).text = object["firstName"] as? String
        (cell.contentView.viewWithTag(2) as UILabel).text = object["lastName"] as? String
        return cell
    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {

        println("You selected cell #\(indexPath.row)!")

    }

}

I think the problem is with viewWithTag(_:), which returns a UIView? (Optional UIView). If it is nil, then the text property access causes the crash. Try to change the code to if let tag1 = cell.contentView.viewWithTag(1) as UILabel { ... } and put a breakpoint there to see what happens. — Romain

Rob Rob · Accepted Answer · 2015-02-08T17:28:18

If you want to use a custom cell layout, I would suggest

Subclass UITableViewCell:

//  CustomTableViewCell.swift

import UIKit

class CustomTableViewCell: UITableViewCell {

    @IBOutlet weak var firstNameLabel: UILabel!
    @IBOutlet weak var lastNameLabel: UILabel!

}

Create table view in storyboard. Add cell prototype to tableview in storyboard. Design that cell prototype (adding whatever labels you want).
Specify the storyboard identifier for the cell prototype to be whatever you want (MyCell in your example).
Specify the base class for the cell prototype to be, in this example, CustomTableViewCell:
Hook up the IBOutlet references between your cell prototype and your UITableViewCell subclass.

Notice the solid bullets to the left of the IBOutlet references. That indicates that the outlet was hooked up correctly.

Implement cellForRowAtIndexPath in your data source, e.g. in Swift 3:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath) as! CustomTableViewCell

    let person = dataArray[indexPath.row]

    cell.firstNameLabel.text = person["firstName"]
    cell.lastNameLabel.text = person["lastName"]

    return cell
}

Or in Swift 2:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("MyCell", forIndexPath: indexPath) as! CustomTableViewCell

    let person = dataArray[indexPath.row]

    cell.firstNameLabel.text = person["firstName"]
    cell.lastNameLabel.text = person["lastName"]

    return cell
}

Note, if using cell prototypes, you do not want to call registerClass in viewDidLoad. The storyboard will automatically register your custom class with the reused identifier for you (because of what you have done in steps 3 and 4).

Unexpectedly found nil while unwrapping an Optional value swift

3 Answers