这是什么意思？ “NSUnknownKeyException”，原因：...该类不是关键字编码符合键X“ [英] What does this mean? "'NSUnknownKeyException', reason: … this class is not key value coding-compliant for the key X"

问题描述

我想尝试将 UILabel 与在我的课程中创建的 IBOutlet 相关联。

I'm trying to link a UILabel with an IBOutlet created in my class.

我的应用程序崩溃，出现以下错误。这是什么意思？

My application is crashing with the following error. What does this mean? How can I fix it?

***由于未捕获异常NSUnknownKeyException终止应用程序，原因：'[< UIViewController 0x6e36ae0> setValue：forUndefinedKey：]：此类不是键值编码兼容的键XXX。'

*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIViewController 0x6e36ae0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key XXX.'

推荐答案

您的视图控制器在您的xib中可能有错误的类。

我下载了您的项目。

Your view controller may have the wrong class in your xib.

I downloaded your project.

您得到的错误是

'NSUnknownKeyException' [< UIViewController 0x3927310> setValue：forUndefinedKey：]：这个类不是键值编码符合键字符串。'

'NSUnknownKeyException', reason: '[<UIViewController 0x3927310> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key string.'

它是由 MainWindow.xib 中的 类的 > UIViewController 而不是 SecondView 。更改为正确的类可解决问题。

It is caused by the Second view controller in MainWindow.xib having a class of UIViewController instead of SecondView. Changing to the correct class resolves the problem.

顺便说一下，在Objective-C中使用string这样的名字是不好的做法。它邀请运行时命名冲突。避免他们即使在一次关闭实践应用程序。命名冲突可能很难跟踪，你不想浪费时间。

By the way, it is bad practice to have names like "string" in Objective-C. It invites a runtime naming collision. Avoid them even in once off practice apps. Naming collisions can be very hard to track down and you don't want to waste the time.

此错误的另一个可能原因：当复制&粘贴元素从一个控制器到另一个，Xcode以某种方式保持该链接到原始控制器，即使在编辑&将此元素重新链接到新控制器中。

Another possible reason for this error: when copying & pasting elements from one controller into another, Xcode somehow keeps that link to the original controller, even after editing & relinking this element into the new controller.

这篇关于这是什么意思？ “NSUnknownKeyException”，原因：...该类不是关键字编码符合键X“的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！