tableView.registerClass in swift is fatal error

Question

I use Xcode7

i register the cell in viewDidLoad()

 let SLQHomeTableViewCellID = "SLQHomeTableViewCellID"
 self.tableView.registerClass(SLQStatusCell.self, forCellReuseIdentifier: SLQHomeTableViewCellID)

then the dataSouce like below:

// MARK: - Table view data source
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of rows
  return statuses?.count ?? 0
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier(SLQHomeTableViewCellID, forIndexPath: indexPath) as! SLQStatusCell
    let status = statuses![indexPath.row]
    cell.status = status
    return cell
}

i also override init()

override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
    super.init(style: style, reuseIdentifier: reuseIdentifier)
    // 初始化UI
    setupUI()

}

but when i run in simulator ,it's a fatal error in register cell ,this line is the error appeared

 self.tableView.registerClass(SLQStatusCell.self, forCellReuseIdentifier: SLQHomeTableViewCellID)

fatal error: unexpectedly found nil while unwrapping an Optional value

i want to why,i run the program in using OC is all right.

Answer 1

If the line with the registerClass method call is causing that error, then chances are good the tableView IBOutlet is not connected. That is the most likely thing on that line of code that would be nil, as it probably has a type of UITableView! which is being implicitly unwrapped.

You can test this by setting a breakpoint and inspecting the value of self.tableView or with a simple print("Table view: \(self.tableView)") statement put above the existing registerClass line.