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标题: ios - 为什么是 "Unknown class"? [打印本页]

作者: 菜鸟教程小白    时间: 2022-12-11 18:30
标题: ios - 为什么是 "Unknown class"?

我是编程初学者,也是 Stack Overflow 的新手。我还在弄清楚代码和这个网站是如何工作的,所以如果我没有正确使用它们,我很抱歉。 (我的母语不是英语,但我会尽我所能解释我的问题)

我使用的是 Xcode 8.1 版和 Swift。

我正在为我的学校项目构建一个应用程序。我已经创建了 To-Do-List App 和 Countdown Timer App。所以,我现在想把它们放在一个应用程序中。

我创建了一个新项目并插入了标签栏 Controller 。然后复制我在 To-Do-List 和 Countdown Timer 应用中使用的所有文件,并设置 Storyboard。

没有警告标记,但是当我运行模拟器时,出现错误并且模拟器停止。我得到的错误是 AppDelegate.swift 中这一行中的“线程 1:信号 SIGABRT”:

class AppDelegate: UIResponder, UIApplicationDelegate {

控制台中的消息是:

2017-01-06 20:32:22.207 PP Final App[61701:3259153] Unknown class PomodoroViewController in Interface Builder file.
2017-01-06 20:32:22.713 PP Final App[61701:3259153] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIViewController 0x7fd7faf075d0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key lbTimer.'
*** First throw call stack:
(
    0   CoreFoundation                      0x00000001100c234b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010fb2321e objc_exception_throw + 48
    2   CoreFoundation                      0x00000001100c2299 -[NSException raise] + 9
    3   Foundation                          0x000000010f63326f -[NSObject(NSKeyValueCoding) setValue:forKey:] + 291
    4   UIKit                               0x000000011067f4ef -[UIViewController setValue:forKey:] + 88
    5   UIKit                               0x00000001108f379e -[UIRuntimeOutletConnection connect] + 109
    6   CoreFoundation                      0x0000000110067590 -[NSArray makeObjectsPerformSelector:] + 256
    7   UIKit                               0x00000001108f2122 -[UINib instantiateWithOwnerptions:] + 1867
    8   UIKit                               0x0000000110685c21 -[UIViewController _loadViewFromNibNamed:bundle:] + 386
    9   UIKit                               0x0000000110686543 -[UIViewController loadView] + 177
    10  UIKit                               0x0000000110686878 -[UIViewController loadViewIfRequired] + 201
    11  UIKit                               0x00000001106870cc -[UIViewController view] + 27
    12  UIKit                               0x00000001106e52df -[UITabBarController transitionFromViewController:toViewController:transition:shouldSetSelected:] + 483
    13  UIKit                               0x00000001106e4721 -[UITabBarController transitionFromViewController:toViewController:] + 59
    14  UIKit                               0x00000001106e05e2 -[UITabBarController _setSelectedViewController:] + 365
    15  UIKit                               0x00000001106e0464 -[UITabBarController setSelectedViewController:] + 234
    16  UIKit                               0x000000011059e6e6 +[UIView(Animation) performWithoutAnimation:] + 90
    17  UIKit                               0x00000001106daa00 -[UITabBarController _selectDefaultViewControllerIfNecessaryWithAppearanceTransitions:] + 354
    18  UIKit                               0x00000001106dbb7a -[UITabBarController viewWillAppear:] + 206
    19  UIKit                               0x000000011068ca0f -[UIViewController _setViewAppearState:isAnimating:] + 692
    20  UIKit                               0x000000011068d11f -[UIViewController __viewWillAppear:] + 147
    21  UIKit                               0x000000011068e913 -[UIViewController viewWillMoveToWindow:] + 507
    22  UIKit                               0x0000000110595151 -[UIView(Hierarchy) _willMoveToWindow:withAncestorView:] + 621
    23  UIKit                               0x00000001105a5cf0 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 451
    24  UIKit                               0x00000001105947a1 -[UIView(Hierarchy) addSubview:] + 838
    25  UIKit                               0x0000000110550f5b -[UIWindow addRootViewControllerViewIfPossible] + 849
    26  UIKit                               0x00000001105513a2 -[UIWindow _setHidden:forced:] + 293
    27  UIKit                               0x0000000110564cb5 -[UIWindow makeKeyAndVisible] + 42
    28  UIKit                               0x00000001104ddc89 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4818
    29  UIKit                               0x00000001104e3de9 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1731
    30  UIKit                               0x00000001104e0f69 -[UIApplication workspaceDidEndTransaction:] + 188
    31  FrontBoardServices                  0x0000000113ed3723 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 24
    32  FrontBoardServices                  0x0000000113ed359c -[FBSSerialQueue _performNext] + 189
    33  FrontBoardServices                  0x0000000113ed3925 -[FBSSerialQueue _performNextFromRunLoopSource] + 45
    34  CoreFoundation                      0x0000000110067311 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    35  CoreFoundation                      0x000000011004c59c __CFRunLoopDoSources0 + 556
    36  CoreFoundation                      0x000000011004ba86 __CFRunLoopRun + 918
    37  CoreFoundation                      0x000000011004b494 CFRunLoopRunSpecific + 420
    38  UIKit                               0x00000001104df7e6 -[UIApplication _run] + 434
    39  UIKit                               0x00000001104e5964 UIApplicationMain + 159
    40  PP Final App                        0x000000010f52c1cf main + 111
    41  libdyld.dylib                       0x000000011373c68d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

在此消息中,我看到“Interface Builder 文件中的未知类 PomodoroViewController”。这就是问题所在,对吧?但我不知道为什么我收到这条消息。文件有问题吗?

我使用 Tab Bar Controller 的方式对吗?

这是番茄钟 View Controller 的代码文件:

番茄 View Controller

import UIKit

class PomodoroViewController: UIViewController {

    @IBOutlet weak var lbTimer: UILabel!

    let pomodoroTime: TimeInterval = 60 * 25 //Pomodoro Timer 25 minutes
    let formatter = DateFormatter()
    var theTime: TimeInterval = 0.0

    override func viewDidLoad(){
        super.viewDidLoad()
        formatter.dateFormat = "mm:ss"
        let startTime = Date(timeIntervalSinceReferenceDate: pomodoroTime)
        lbTimer.text = formatter.string(from: startTime)
    }

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

    @IBAction func countDown(_ sender: UIButton) {
        theTime = pomodoroTime
        Timer.scheduledTimer(timeInterval: 1.0,
                             target: self,
                             selector: #selector(PomodoroViewController.tickTimer(timer),
                             userInfo: nil,
                             repeats: true)
    }

    func tickTimer(timer: Timer){
        theTime -= 1.0
        let newTime = Date(timeIntervalSinceReferenceDate: theTime)
        if theTime < 0.1 {
            timer.invalidate()
        }
    }

}

Storyboard是这样的: storyboard



Best Answer-推荐答案


这个错误的意思是:

  1. 你有一个 Storyboard(或者可能是一个 xib),它说其中一个 View Controller 是 PomodoroViewController。但是...
  2. PomodoroViewController 应用运行时不存在。

消息说 iOS 试图找到 PomodoroViewController 但它不存在,因此它尝试使用 UIViewController 代替。除了 UIViewController 没有 lbTimer 属性,这会导致应用崩溃。

发生这种情况的原因有几个:

在第二种情况下,确保在 Xcode 窗口右侧的文件检查器中检查了该文件:

enter image description here

关于ios - 为什么是 "Unknown class"?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41513564/






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