在Xcode中传递segue时未捕获的异常

Question

函数didSelectRowAtIndexPath与未捕获的异常崩溃并导致class AppDelegate: UIResponder, UIApplicationDelegate{与Thread1：信号SIGABRT错误

我认为这是代表们的错误发布。关于如何处理这个问题的任何想法？

import UIKit

class UnitTableViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, UIActionSheetDelegate {
    let cellID = "cellID"

    @IBOutlet var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.dataSource = self
        tableView.delegate = self
    }

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

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 2
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        var cell = tableView.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell!
        if !(cell != nil){
            cell = UITableViewCell(style:.Default, reuseIdentifier: cellID)
        }
        if indexPath.row == 0
        {
            cell.textLabel?.text = "2016"
        }
        else {
            cell.textLabel?.text = "2017"
        }

        return cell;
    }

    func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        return String (format: "Please select year of study", section + 1)
    }

    func tableView(tableView: UITableView, titleForFooterInSection section: Int) -> String? {
        return String (format: "Thankyou for your selection", section + 1)
    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        switch (indexPath.row) {
        case 0:
            [self.performSegueWithIdentifier("2015Segue'", sender: self)]
        case 1:
            [self.performSegueWithIdentifier("2016Segue'", sender: self)]
        default:
            break;
        }
       // NSLog("Row %ld selected on Section %ld", indexPath.row + 1, indexPath.section + 1)
        tableView.deselectRowAtIndexPath(indexPath, animated: true)
    }

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