EXC_BAD_INSTRUCTION breakpoint when starting app xCode - uitableview

Question

I have a tableview in my app and when I start my app it crashes on the following function.
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
// Configure the cell...
let cellId: NSString = "Cell"
var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellId) as UITableViewCell
}
It crashes on the line of var cell
It gives the following error:
I can't figure out what's wrong with my code.
The whole function:
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
// Configure the cell...
let cellId: NSString = "Cell"
var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellId) as UITableViewCell
let data: NSManagedObject = mylist[ip.row] as NSManagedObject
cell.textLabel.text = data.valueForKeyPath("voornaam") as String
cell.detailTextLabel.text = data.valueForKeyPath("achternaam") as String
return cell
}
EDIT:
What I got now:(Still gives the same error)
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell? {
// Configure the cell...
let cellId: NSString = "Cell"
var cell: UITableViewCell? = tableView?.dequeueReusableCellWithIdentifier(cellId) as? UITableViewCell
if cell == nil {
cell = UITableViewCell(style: .Subtitle, reuseIdentifier: cellId)
}
let data: NSManagedObject = mylist[indexPath.row] as NSManagedObject
cell!.textLabel.text = data.valueForKey("voornaam") as String
cell!.detailTextLabel.text = data.valueForKey("achternaam") as String
//cell!.textLabel.text = "Hoi"
return cell
}

Answer 1

This is happening because the as operator is defined to cast an object to a given type and crash if the conversion fails. In this case, the call to dequeue returns nil the first time you call it. You need to use the as? operator, which will attempt to cast the given object to a type, and return an optional that has a value only if the conversion succeeded:
var cell: UITableViewCell? = tableView.dequeueReusableCellWithIdentifier(cellId) as? UITableViewCell
if cell == nil {
cell = UITableViewCell(style: .Subtitle, reuseIdentifier: cellId)
}
...
Because cell is now an optional value, use cell! when you want to call methods on it to force-unwrap the UITableViewCell inside it.
Additionally, your code had a second problem: it never created a fresh cell. dequeue will return nil the first time it's called on your table view. You need to instantiate a new UITableViewCell as in my code sample and then return it from the cellFor... method. The table view will then save the cell and return it on future calls to dequeue.

Answer 2

First off, why are you doing an optional binding on line if let ip = indexPath? This argument is not optional and you don't need to do optional binding or unwrap it. But this shouldn't cause your code to crash.
Remove your let data line and assign literal strings to your cells and see if it still crashes.

Answer 3

May I suggest that you check to see if you set the tableview's delegates? I made that mistake once in the flurry of setting everything else up.

Answer 4

Perhaps it is too late but I like to share my experience. I had similar error as I copied the entire code from another project. So I think the variables and functions won't be recognised so I had to drag them (cntr+drag) then it is solved.
Sorry if I couldn't explain better. I am new this.