从Swift中的UITextView中获取单词

Question

我知道这个问题已经在Objective-C中解决了,但我在Swift中没有看到任何解决方案.我试图从这篇文章转换解决方案代码,但我收到错误:

func textTapped(recognizer: UITapGestureRecognizer){

    var textView: UITextView = recognizer.view as UITextView
    var layoutManager: NSLayoutManager = textView.layoutManager
    var location: CGPoint = recognizer.locationInView(textView)
    location.x -= textView.textContainerInset.left
    location.y -= textView.textContainerInset.top

    var charIndex: Int
    charIndex = layoutManager.characterIndexForPoint(location, inTextContainer: textView.textContainer, fractionOfDistanceBetweenInsertionPoints: nil)

    if charIndex < textView.textStorage.length {
        // do the stuff
        println(charIndex)
    }
}

我认为问题出在这一行(见这里的错误):

 var textView: UITextView = recognizer.view as UITextView

...我根据这一行从Objective-C转换而来:

 UITextView *textView = (UITextView *)recognizer.view;

最后,我也对如何调用此函数表示怀疑.据我了解,该函数应该传递给viewDidLoad()中的Selector,如下所示:

 let aSelector: Selector = "textTapped:"   

 let tapGesture = UITapGestureRecognizer(target: self, action: aSelector)
 tapGesture.numberOfTapsRequired = 1
 view.addGestureRecognizer(tapGesture)

因为我得到了前面提到的错误,我不确定它是否会起作用.但我想我还需要将textTapped函数(识别器)中的参数传递给Selector.但是,我已经读过你只能传递函数而不是任何参数.

Answer 1

适用于Swift 3.0或以上版本

将点击手势添加到UITextView

let tapGesture = UITapGestureRecognizer(target: self, action: #selector(tapOnTextView(_:)))
textView.addGestureRecognizer(tapGesture)

添加tap处理程序方法

@objc private final func tapOnTextView(_ tapGesture: UITapGestureRecognizer){

  let point = tapGesture.location(in: textView)
  if let detectedWord = getWordAtPosition(point)
  {

  }
}

从点上得到消息

private final func getWordAtPosition(_ point: CGPoint) -> String?{
if let textPosition = textView.closestPosition(to: point)
{
  if let range = textView.tokenizer.rangeEnclosingPosition(textPosition, with: .word, inDirection: 1)
  {
    return textView.text(in: range)
  }
}
return nil}

Answer 2

您需要添加UITapGestureRecognizer到UITextView您希望能够挖掘.你现在正在加入UITapGestureRecognizer你ViewController的view.这就是演员让你陷入困境的原因.你正试图把一个UIView转变成一个UITextView.

let tapGesture = UITapGestureRecognizer(target: self, action: #selector(textTapped))
tapGesture.numberOfTapsRequired = 1
myTextView.addGestureRecognizer(tapGesture)

从技术上讲,它recognizer.view是一个可选的类型(UIView!),可能是nil,但似乎不太textTapped()可能被称为未设置的类型.同样,layoutManager是类型NSLayoutManager!.为了安全起见,Swift的方法是:

guard let textView = recognizer.view as? UITextView, let layoutManager = textView.layoutManager else {
    return
}
// code using textView and layoutManager goes here

事实上,如果你用这种方式编写它,你就不会崩溃,因为UIViewto 的条件转换UITextView不会成功.

要使这一切正常工作,请将属性添加到您将在textTapped例程中提取的属性字符串中:

var beginning = NSMutableAttributedString(string: "To the north you see a ")
var attrs = [NSFontAttributeName: UIFont.systemFontOfSize(19.0), "idnum": "1", "desc": "old building"]
var condemned = NSMutableAttributedString(string: "condemned building", attributes: attrs)
beginning.appendAttributedString(condemned)
attrs = [NSFontAttributeName: UIFont.systemFontOfSize(19.0), "idnum": "2", "desc": "lake"]
var lake = NSMutableAttributedString(string: " on a small lake", attributes: attrs)
beginning.appendAttributedString(lake)
myTextView.attributedText = beginning

这是完整的textTapped:

@objc func textTapped(recognizer: UITapGestureRecognizer) {
    guard let textView = recognizer.view as? UITextView, let layoutManager = textView.layoutManager else {
        return
    }
    var location: CGPoint = recognizer.locationInView(textView)
    location.x -= textView.textContainerInset.left
    location.y -= textView.textContainerInset.top

    /* 
    Here is what the Documentation looks like :

    Returns the index of the character falling under the given point,    
    expressed in the given container's coordinate system.  
    If no character is under the point, the nearest character is returned, 
    where nearest is defined according to the requirements of selection by touch or mouse.  
    This is not simply equivalent to taking the result of the corresponding 
    glyph index method and converting it to a character index, because in some 
    cases a single glyph represents more than one selectable character, for example an fi ligature glyph.
    In that case, there will be an insertion point within the glyph, 
    and this method will return one character or the other, depending on whether the specified 
    point lies to the left or the right of that insertion point.  
    In general, this method will return only character indexes for which there 
    is an insertion point (see next method).  The partial fraction is a fraction of the distance 
    from the insertion point logically before the given character to the next one, 
    which may be either to the right or to the left depending on directionality.
    */
    var charIndex = layoutManager.characterIndexForPoint(location, inTextContainer: textView.textContainer, fractionOfDistanceBetweenInsertionPoints: nil)

    guard charIndex < textView.textStorage.length else {
        return
    }

    var range = NSRange(location: 0, length: 0)
    if let idval = textView.attributedText?.attribute("idnum", atIndex: charIndex, effectiveRange: &range) as? NSString {
        print("id value: \(idval)")
        print("charIndex: \(charIndex)")
        print("range.location = \(range.location)")
        print("range.length = \(range.length)")
        let tappedPhrase = (textView.attributedText.string as NSString).substringWithRange(range)
        print("tapped phrase: \(tappedPhrase)")
        var mutableText = textView.attributedText.mutableCopy() as NSMutableAttributedString
        mutableText.addAttributes([NSForegroundColorAttributeName: UIColor.redColor()], range: range)
        textView.attributedText = mutableText
    }
    if let desc = textView.attributedText?.attribute("desc", atIndex: charIndex, effectiveRange: &range) as? NSString {
        print("desc: \(desc)")
    }
}