尝试执行 segue 导致 "terminating with uncaught exception of type NSException"

Question

我有一个 UITableView VC，其中的单元格链接到 prepare for segue 函数，这很有效。它移动到正确的 VC。我在链接到调用 performForSegue 的方法的导航项上添加了 rightBarButtonItem，并为其提供了正确的标识符。在我单击右侧按钮之前，一切都运行良好。当我这样做时，我得到： "First throw call stack. terminating with uncaught exception of type NSException" 有人可以帮助我并指出正确的方向吗？下面的代码和打印清单。谢谢你。

class AssignNumberOfRoomsForFloorsVC: UITableViewController {

//MARK: - Properties

private var managedObjectContext: NSManagedObjectContext!

private var storedFloors = [Floors]()


//MARK: - Actions

override func viewDidLoad() {
    super.viewDidLoad()
    managedObjectContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    loadFloorData()
    self.tableView.reloadData()
    self.navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.done, target: self, action: Selector(("navigateToNextViewController")))

}

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

private func loadFloorData() {
    let request: NSFetchRequest<Floors> = Floors.fetchRequest()
    request.returnsObjectsAsFaults = false
    do {
        storedFloors = try managedObjectContext.fetch(request)
    }
    catch {
        print("could not load data from core \(error.localizedDescription)")
    }
}

private func navigateToNextViewController(){
    self.performSegue(withIdentifier: "room and alarm type", sender: self)
}



// MARK: - Table view data source

override func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return storedFloors.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "floor cell", for: indexPath) as! FloorCell
    let floorItem = storedFloors[indexPath.row]
    cell.floorNumberTxt.text = String(floorItem.floorNumber)
    return cell
}

// MARK: - Navigation

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    var selectedRow = self.tableView.indexPathForSelectedRow
    let floorItem = storedFloors[(selectedRow?.row)!]
    let destinationController = segue.destination
    if let assignRoomsVC = destinationController as? DeclareRoomsVC {
        if let identifier = segue.identifier {
            switch identifier {
            case "assign number of rooms":
                let _ = assignRoomsVC.view
                assignRoomsVC.floorNumberTxt.text = String(floorItem.floorNumber)
                assignRoomsVC.selectedFloor = floorItem.floorNumber
            default: break
            }
        }
    }
}

}

这是控制台中的消息：

2017-03-26 21:50:28.041 PDCiPad[10433:292572] -[PDCiPad.AssignNumberOfRoomsForFloorsVC navigateToNextViewController]: unrecognized selector sent to instance 0x7ff5b7c326c0

2017-03-26 21:50:28.219 PDCiPad[10433:292572] * 由于未捕获的异常终止应用程序 'NSInvalidArgumentException'，原因：'-[PDCiPad.AssignNumberOfRoomsForFloorsVC navigateToNextViewController]：无法识别的选择器发送到实例 0x7ff5b7c326c0' * 首先抛出调用栈： ( 0 CoreFoundation 0x000000010db79d4b exceptionPreprocess + 171 1 libobjc.A.dylib 0x000000010d1ba21e objc_exception_throw + 48 2 CoreFoundation 0x000000010dbe9f04 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132 3 核心基础 0x000000010daff005 ___forwarding_ + 1013 4 核心基础 0x000000010dafeb88 _CF_forwarding_prep_0 + 120 5 UIKit 0x000000010e6b28bc -[UIApplication sendAction:to:from:forEvent:] + 83 6 UIKit 0x000000010eaf44a1 -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 149 7 UIKit 0x000000010e6b28bc -[UIApplication sendAction:to:from:forEvent:] + 83 8 UIKit 0x000000010e838c38 -[UIControl sendAction:to:forEvent:] + 67 9 UIKit 0x000000010e838f51 -[UIControl _sendActionsForEvents:withEvent:] + 444 10 UIKit 0x000000010e8390db -[UIControl _sendActionsForEvents:withEvent:] + 838 11 UIKit 0x000000010e837e4d -[UIControl touchesEnded:withEvent:] + 668 12 UIKit 0x000000010e720545 -[UIWindow _sendTouchesForEvent:] + 2747 13 UIKit 0x000000010e721c33 -[UIWindow 发送事件：] + 4011 14 UIKit 0x000000010e6ce9ab -[UIApplication sendEvent:] + 371 15 UIKit 0x000000010eebb72d dispatchPreprocessedEventFromEventQueue + 3248 16 UIKit 0x000000010eeb4463 __handleEventQueue + 4879 17 核心基础 0x000000010db1e761 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17 18 核心基础 0x000000010db0398c __CFRunLoopDoSources0 + 556 19 核心基础 0x000000010db02e76 __CFRunLoopRun + 918 20 核心基础 0x000000010db02884 CFRunLoopRunSpecific + 420 21 图形服务 0x0000000113908a6f GSEventRunModal + 161 22 UIKit 0x000000010e6b0c68 UIApplicationMain + 159 23 PDCiPad 0x000000010cad8c1f 主 + 111 24 libdyld.dylib 0x0000000111a3268d 开始 + 1 ) libc++abi.dylib：以 NSException

类型的未捕获异常终止

Answer 1

使用Swift 3 selector语法

#selector(navigateToNextViewController)

Answer 2

当您点击 UIBarButtonItem 时，selectedRow 是 nil 因为您使用 indexPathForSelectedRow 而您没有 select 任何行。

如果单击 UIBarButtonItem 或 tableView 单元格，将调用

override func prepare(for segue: UIStoryboardSegue, sender: Any?)。

因此，当您单击 tableView 单元格时它会起作用，因为 self.tableView.indexPathForSelectedRow 将 return selected 单元格的索引。但是会 return nil 为你 UIBarButtonItem.

最后，如果你在 nil 值上使用 !，你会崩溃。

尝试执行 segue 导致 "terminating with uncaught exception of type NSException"

attempt to perform segue leads to "terminating with uncaught exception of type NSException"

swift

swift3

segue

uistoryboardsegue