ios - 未捕获的异常 : This class is not key value coding-compliant

Question

这个问题已经有答案了:

Xcode - How to fix 'NSUnknownKeyException', reason: … this class is not key value coding-compliant for the key X" error? (81 个回答)

已关闭 7 年前。

我正在关注a tutorial titled "Swift Tutorial for iOS : NSFileManager Persisting Data" ，并且我在 29 分钟左右或之后遇到了错误。当我尝试在 iOS 模拟器上运行它时，收到错误:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key theLoadMethod.'

显然基于错误，我认为问题是我的 theLoadMethod 。这是我在 ViewController 中作为该项目的一部分编写的全部代码:

let theDocumentsFolder = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as String
let theFileName     = "/theUserFile.txt"
let thePath         = theDocumentsFolder.stringByAppendingString(theFileName)


class ViewController: UIViewController {

@IBOutlet weak var nameTextField: UITextField!
@IBOutlet weak var lastNameTextField: UITextField!
@IBOutlet weak var ageTextField: UITextField!

@IBOutlet weak var theLabel: UILabel!

// The save method
@IBAction func theSaveMethod(sender: AnyObject) {
    var name        = nameTextField.text
    var lastName    = lastNameTextField.text
    var age         = ageTextField.text

    var theString   =   "The user's information is: \(name), \(lastName), \(age)"

    let theFileManager = NSFileManager.defaultManager()

    if !theFileManager.fileExistsAtPath(thePath) {

        var writeError:NSError?
        let fileToBeWritten = theString.writeToFile(thePath, atomically: true, encoding: NSUTF8StringEncoding, error: &writeError)

        if writeError == nil {
            println("No errors. Added: \(theString)")
        } else {
            println("Encountered an error. Error is: \(writeError)")
        }

    } else {
        println("File already exists")
    }

    nameTextField.resignFirstResponder()
    lastNameTextField.resignFirstResponder()
    ageTextField.resignFirstResponder()
}

@IBAction func theLoadMethod(sender: AnyObject) {
    let infoFromFile:String = String.stringWithContentsOfFile(thePath, encoding: NSUTF8StringEncoding, error: nil)!

    theLabel.text = infoFromFile
}

我是不是做错了什么？据我所知，我的所有 iOS 屏幕元素都已正确命名和链接。

Answer 1

这通常是由 Storyboard到不存在的属性的链接引起的。仔细检查 Storyboard中对象的所有链接。此外，如果您更改了属性或方法的名称或拼写，它仍然可以引用旧的。