Simple UITableView in Swift - unexpectedly found nil

Question

Pretty simple code:

func numberOfSectionsInTableView(tableView: UITableView?) -> Int {
    return 1
}

func tableView(tableView:UITableView!, numberOfRowsInSection section:Int) -> Int {
    return 5
}


func tableView(tableView:UITableView!, cellForRowAtIndexPath indexPath:NSIndexPath!) -> UITableViewCell! {
    let cell: BookTableViewCell = BookTableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: "BookCell")
    println("ip: \(indexPath.row)")
    cell.bookLabel.text = "test"

    return cell
}

On the cell.bookLabel.text line I get this:

fatal error: unexpectedly found nil while unwrapping an Optional value

The BookTableViewCell is defined like this:

class BookTableViewCell: UITableViewCell {

    @IBOutlet var bookLabel: UILabel

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

    override func setSelected(selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        // Configure the view for the selected state
    }

}

And bookLabel is correctly hooked up in a Prototype cell in the Storyboard. Why am I getting this error?

Solution 1

When you create a view in code, its IBOutlet properties don't get hooked up properly. You want the version that you get back from dequeueReusableCellWithIdentifier:

let cell = tableView.dequeueReusableCellWithIdentifier("BookCell") as BookTableViewCell

Solution 2

If you're using storyboard, make sure you don't have this line at the start of your file:

self.tableView.registerClass(CustomTableViewCell.self, forCellReuseIdentifier: "customCell")

It will overwrite the storyboard and as a result, the outlet links in the storyboard are ignored.

Solution 3

I was getting this error because I didn't have the identifier written in the Storyboard of the Custom Cell.

Also make sure it matches you code in:

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
    {

        let cell = tableView.dequeueReusableCellWithIdentifier("CustomTableCell") as CustomTableCell

        ...
    }

Solution 4

Possibly that your view in Main.Storyboard lost its IBOutlet reference in ViewController file, just link it again.

Solution 5

Do not forget to register nib (tested with Swift3), e. g. inside override func viewDidLoad():

self.tableView.register(UINib(nibName: "BookTableViewCell", bundle: nil), forCellReuseIdentifier: "BookCell")

View more solutions

Comments

[Vincil Bishop]

This was the right answer for me...was pulling my hair out.

[Cesare]

Thanks so much. I was so used to write this when I was doing everything programmatically.

[Adam Fendley]

In my case I had a stale IBOutlet reference that was causing this error. Thanks for the suggestion.

[Giovanni Palusa]

Finally a good answer on this question - I spent the last hour of trying to figure this one out...

[Lax]

Instead, to register the cell, use self.tableView.register(UINib(nibName: LXIssueConstants.issueCell, bundle: nil), forCellReuseIdentifier: LXIssueConstants.issueCell)

[stepheaw]

This was the case using Xamarin iOS storyboards. I just needed to clear the TableView name property, save the storyboard. Re-enter the TableView name, and then delete bin and obj folders