如何修复“致命错误：无法索引空缓冲区” [英] How can I fix "fatal error: can't index empty buffer"

问题描述

我尝试为文本字段开发自定义自动填充。代码可以工作，但是如果我删除了所有的输入，调试器会说：致命错误：无法对空缓冲区进行索引，在写入的行中： if createdArrayInDependencyOfInput [indexOfArray] == textFieldText& amp ; indexOfArray> = 0&&& currentCountOfInput> = 1

I try to develop a custom autocompletion for a textfield. The code works but if I delete all my input, the debugger says: "fatal error: can't index empty buffer" in the line where is written: if createdArrayInDependencyOfInput[indexOfArray] == textFieldText && indexOfArray >= 0 && currentCountOfInput >= 1

以下是整个代码：

@IBOutlet weak var MyTextField: UITextField!
@IBOutlet weak var MyPlaceholderTextField: UITextField!

var arrayOfSubjects: [String] = ["Informatik", "Italienisch", "Lateinisch", "Biologie", "Mathematik"]
var createdArrayInDependencyOfInput: [String] = []
var formerCountOfInput: Int = 0
var foundSubject: Bool = false
var indexOfArray: Int = 0

func printValue(value: Int) {
    println("\(value)")
}

func convertStringOfArrayToAnArrayOfCharacters(array: [String], withIndex indexNumber: Int) -> [String] {
    var arrayOfCharacters: [String] = []
    if indexNumber <= array.count - 1 {
        for character in array[indexNumber] {
            var string = String(character)
            arrayOfCharacters.append(string)
        }
    }
    return arrayOfCharacters
}

@IBAction func MyTextFieldEditingChanged(sender: AnyObject) {
    var currentCountOfInput: Int = countElements("\(MyTextField.text)")
    var countOfRun: Int = 0


    func backspaceWasPressed() -> Bool {
        if currentCountOfInput < formerCountOfInput {
            return true
        }
        else {
            return false
        }
    }

    func concatenateArrayOfCharactersToString(array: [String]) -> String {
        var arrayForDelegate: [String] = [""]
        var positionOfRun: Int = 0
        if arrayForDelegate[0] == "" {
            arrayForDelegate.removeLast()
        }
        while positionOfRun <= array.endIndex - 1{
            arrayForDelegate.append(String(array[positionOfRun]))
            positionOfRun += 1
        }

        while (arrayForDelegate.endIndex - 1) >= 1 {
            arrayForDelegate[0] = arrayForDelegate[0] + arrayForDelegate[1]
            arrayForDelegate.removeAtIndex(1)
        }
        if currentCountOfInput >= 1 {
            return arrayForDelegate[0]
        }
        else {
            return ""
        }
    }


    while countOfRun < arrayOfSubjects.count {
        if !backspaceWasPressed() {
            var convertedStringInFormOfArrayOfStrings: [String] = convertStringOfArrayToAnArrayOfCharacters(arrayOfSubjects, withIndex: countOfRun)
            if currentCountOfInput == 1 {
                createdArrayInDependencyOfInput.append(convertedStringInFormOfArrayOfStrings[currentCountOfInput-1])
            }
            else if countOfRun >= 0 {
                if countElements(arrayOfSubjects[countOfRun]) != countElements(createdArrayInDependencyOfInput[countOfRun]){
                createdArrayInDependencyOfInput[countOfRun] = createdArrayInDependencyOfInput[countOfRun] + convertedStringInFormOfArrayOfStrings[currentCountOfInput-1]
                }
            }
            countOfRun += 1
        }
        else if backspaceWasPressed() && createdArrayInDependencyOfInput != [] {
            var convertedString: [String] = convertStringOfArrayToAnArrayOfCharacters(createdArrayInDependencyOfInput, withIndex: countOfRun)
            if countElements(arrayOfSubjects[countOfRun]) > currentCountOfInput  && currentCountOfInput >= 0 {
                convertedString.removeLast()
            }
            createdArrayInDependencyOfInput[countOfRun] = concatenateArrayOfCharactersToString(convertedString)
            countOfRun += 1
        }

    }
    if countElements(createdArrayInDependencyOfInput[0]) == 0 {
        createdArrayInDependencyOfInput.removeAll(keepCapacity: false)
    }

    while !foundSubject {
        var textFieldText: String = MyTextField.text

        if textFieldText.isEmpty {
            createdArrayInDependencyOfInput.removeAll(keepCapacity: false)
        }
        if createdArrayInDependencyOfInput[indexOfArray] == textFieldText && indexOfArray >= 0 && currentCountOfInput >= 1 {
            MyPlaceholderTextField.text = arrayOfSubjects[indexOfArray]
            foundSubject = true
            break
        }
        else {
            MyPlaceholderTextField.text = ""
            foundSubject = false
            indexOfArray += 1
        }
    }
    foundSubject = false
    formerCountOfInput = currentCountOfInput
}

override func viewDidLoad() {
    super.viewDidLoad()
    MyTextField.becomeFirstResponder()
    MyPlaceholderTextField.textColor = UIColor.lightGrayColor()
}

知道有人解决这个问题吗？
感谢您的关注！

Know anybody the solve for this problem? Thank You for Your attention!

推荐答案

该错误意味着 createdArrayInDependencyOfInput 为空。你在清除它之前给出错误的行：

That error means createdArrayInDependencyOfInput is empty. You're clearing it just before the line that gives you the error:

if textFieldText.isEmpty {
        createdArrayInDependencyOfInput.removeAll(keepCapacity: false)
    }

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