我正在关注标题为“
iOS的快速教程：NSFileManager持久数据”的教程，并且在29分钟左右前后遇到错误。当我尝试在iOS模拟器上运行它时，收到错误消息：

由于未捕获的异常’NSUnknownKeyException’而终止应用程序，原因：’[setValue：forUndefinedKey：]：此类与键theLoadMethod的键值编码兼容。

显然是基于错误，我认为问题是我的theLoadMethod。这是我作为该项目的一部分在ViewController中编写的 所有 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
}

我做错了什么吗？据我所知，我在屏幕上的所有iOS元素均已正确命名和链接。