Question

长时间用户，第一次发布海报，所以如果我在提出问题时出错，我很抱歉。我已经研究了几个小时了，我已经决定是时候问专家了。我也搜索了所有已经“回答”和工作的类似问题，这让我相信它们已经过时了。

我试图从稍后将在代码中使用的UITextview中获取抽头单词。例如，文本视图中有一段单词：

“最初的时间投资回报要小得多，因为他交易了公司汗水资产的前期成本，但潜在的长期支出要大得多”。

我希望能够点击一个词，例如'投资'，并通过另一个功能来定义它。然而，只需点击该单词，就会导致程序崩溃，而且我没有收到轻敲的单词。

我实现了一个轻敲手势识别器：

let tap = UITapGestureRecognizer(target: self, action: #selector(tapResponse(_:)))
    tap.delegate = self
    tvEditor.addGestureRecognizer(tap)

然后编写了函数：2

func tapResponse(recognizer: UITapGestureRecognizer) {
    let location: CGPoint = recognizer.locationInView(tvEditor)
    let position: CGPoint = CGPointMake(location.x, location.y)
    let tapPosition: UITextPosition = tvEditor.closestPositionToPoint(position)!
    let textRange: UITextRange = tvEditor.tokenizer.rangeEnclosingPosition(tapPosition, withGranularity: UITextGranularity.Word, inDirection: 1)!

    let tappedWord: String = tvEditor.textInRange(textRange)!
    print("tapped word : %@", tappedWord)
}

理想情况下，这应该从Textview的抽头部分获取位置，通过获取.x＆amp ;,取得位置。 .y，然后在最接近位置的位置浏览Textview，找到包含粒度位置的范围（以返回单词），并设置内容作为一个字符串，我目前只是打印到控制台。但是，在点击这个词时，我收到了这次崩溃。3

以及“致命错误：在解除控制台中的”可选值“时意外发现nil。

非常感谢任何帮助。我可能只是遗漏了一些简单的东西，或者它可能会复杂得多。

Answer 1

每当在单词之间的空白处收到抽头时，TextView返回的tapPosition可以为nil nil。
Swift有一个名为optional ?的新运算符，它告诉编译器变量可能有nil值。如果在变量名称之后没有使用?，则表明该变量永远不会为零值。
在Swift中，使用!运算符意味着您强制编译器强制从可选变量中提取值。因此，在这种情况下，如果变量的值为nil，它将在强制时崩溃。

所以，实际发生的是

您正在创建变量let tapPosition: UITextPosition，let textRange: UITextRange并且let tappedWord: String不是可选的
方法myTextView.closestPositionToPoint(position)的返回类型，tvEditor.textInRange(textRange)是可选变量UITextPosition?，String?
将可选变量的值分配给非可选变量需要!
该方法返回nil，并且您强制它获取值!导致 CRASH

你能做什么

在强制使用任何可选变量之前，请确保使用
确定它有一些值
```
if variable != nil
{
    print(variable!)
}
```

正确的方法是

func tapResponse(recognizer: UITapGestureRecognizer) {
    let location: CGPoint = recognizer.locationInView(myTextView)
    let position: CGPoint = CGPointMake(location.x, location.y)
    let tapPosition: UITextPosition? = myTextView.closestPositionToPoint(position)
    if tapPosition != nil {
        let textRange: UITextRange? = myTextView.tokenizer.rangeEnclosingPosition(tapPosition!, withGranularity: UITextGranularity.Word, inDirection: 1)
        if textRange != nil
        {
            let tappedWord: String? = myTextView.textInRange(textRange!)
            print("tapped word : ", tappedWord)
        }
    }
}

Answer 2

Swift 3.0答案 - 截至2016年7月1日工作

在我的ViewDidLoad（） -

中

我使用之前VC中的文本，因此我的变量“theText”已经被声明。我添加了一个已经注明的示例字符串。

 //Create a variable of the text you wish to attribute.

 let textToAttribute = theText  // or "This is sample text"

 // Break your string in to an array, to loop through it.

    let textToAttributeArray = textToAttribute.componentsSeparatedByString(" ")

 // Define a variable as an NSMutableAttributedString() so you can append to it in your loop. 

    let attributedText = NSMutableAttributedString()


 // Create a For - In loop that goes through each word your wish to attribute.

    for word in textToAttributeArray{

    // Create a pending attribution variable. Add a space for linking back together so that it doesn't looklikethis.

    let attributePending = NSMutableAttributedString(string: word + " ")

    // Set an attribute on part of the string, with a length of the word.

    let myRange = NSRange(location: 0, length: word.characters.count)

    // Create a custom attribute to get the value of the word tapped

    let myCustomAttribute = [ "Tapped Word:": word]

    // Add the attribute to your pending attribute variable

    attributePending.addAttributes(myCustomAttribute, range: myRange)

       print(word)
        print(attributePending)

     //append 'attributePending' to your attributedText variable.

        attributedText.appendAttributedString(attributePending) ///////

        print(attributedText)

    }

textView.attributedText = attributedText // Add your attributed text to textview.

现在我们将添加一个水龙头手势识别器来注册水龙头。

let tap = UITapGestureRecognizer(target: self, action: #selector(HandleTap(_:)))
    tap.delegate = self
    textView.addGestureRecognizer(tap) // add gesture recognizer to text view.

现在我们在viewDidLoad（）

下声明一个函数

func HandleTap(sender: UITapGestureRecognizer) {

    let myTextView = sender.view as! UITextView //sender is TextView
    let layoutManager = myTextView.layoutManager //Set layout manager

    // location of tap in myTextView coordinates

    var location = sender.locationInView(myTextView)
    location.x -= myTextView.textContainerInset.left;
    location.y -= myTextView.textContainerInset.top;

    // character index at tap location
    let characterIndex = layoutManager.characterIndexForPoint(location, inTextContainer: myTextView.textContainer, fractionOfDistanceBetweenInsertionPoints: nil)

    // if index is valid then do something.
    if characterIndex < myTextView.textStorage.length {

        // print the character index
        print("Your character is at index: \(characterIndex)") //optional character index.

        // print the character at the index
        let myRange = NSRange(location: characterIndex, length: 1)
        let substring = (myTextView.attributedText.string as NSString).substringWithRange(myRange)
        print("character at index: \(substring)")

        // check if the tap location has a certain attribute
        let attributeName = "Tapped Word:" //make sure this matches the name in viewDidLoad()
        let attributeValue = myTextView.attributedText.attribute(attributeName, atIndex: characterIndex, effectiveRange: nil) as? String
        if let value = attributeValue {
            print("You tapped on \(attributeName) and the value is: \(value)")
        }

    }
}

Answer 3

除了@AmitSingh的回答，这是更新的Swift 3.0版本：

    func didTapTextView(recognizer: UITapGestureRecognizer) {
    let location: CGPoint = recognizer.location(in: textView)
    let position: CGPoint = CGPoint(x: location.x, y: location.y)
    let tapPosition: UITextPosition? = textView.closestPosition(to: position)
    if tapPosition != nil {
        let textRange: UITextRange? = textView.tokenizer.rangeEnclosingPosition(tapPosition!, with: UITextGranularity.word, inDirection: 1)
        if textRange != nil
        {
            let tappedWord: String? = textView.text(in: textRange!)
            print("tapped word : ", tappedWord!)
        }
    }
}

其他代码与他的代码相同。

希望它有所帮助！

Swift - Textview识别窃听的单词不起作用

3 个答案: