ios - 如何让 UITextView 检测主题标签？

Question

我知道 UITextView 默认可以检测 URL，但我怎样才能让它检测到 hashtags(#)？

它不需要在打字时检测主题标签，但是 viewDidLoad 文本设置在 UITextView 中，所以我想检测主题标签作为颜色或其他东西.

我一直在使用ActiveLabel ，但这仅适用于 UILabel，我需要 UITextView 具有的滚动功能。

Answer 1

这应该适合你

1. 创建一个任意名称的新 swift 文件(UITextViewHashtagExtension.swift)

2. 在下面插入这段代码:

   import UIKit
   
   extension UITextView {
   
   func resolveHashTags(){
   
       // turn string in to NSString
       let nsText:NSString = self.text
   
       // this needs to be an array of NSString.  String does not work.
       let words:[NSString] = nsText.componentsSeparatedByString(" ")
   
       // you can't set the font size in the storyboard anymore, since it gets overridden here.
       let attrs = [
           NSFontAttributeName : UIFont.systemFontOfSize(17.0)
       ]
   
       // you can staple URLs onto attributed strings
       let attrString = NSMutableAttributedString(string: nsText as String, attributes:attrs)
   
       // tag each word if it has a hashtag
       for word in words {
   
           // found a word that is prepended by a hashtag!
           // homework for you: implement @mentions here too.
           if word.hasPrefix("#") {
   
               // a range is the character position, followed by how many characters are in the word.
               // we need this because we staple the "href" to this range.
               let matchRange:NSRange = nsText.rangeOfString(word as String)
   
               // convert the word from NSString to String
               // this allows us to call "dropFirst" to remove the hashtag
               var stringifiedWord:String = word as String
   
               // drop the hashtag
               stringifiedWord = String(stringifiedWord.characters.dropFirst())
   
               // check to see if the hashtag has numbers.
               // ribl is "#1" shouldn't be considered a hashtag.
               let digits = NSCharacterSet.decimalDigitCharacterSet()
   
               if let numbersExist = stringifiedWord.rangeOfCharacterFromSet(digits) {
                   // hashtag contains a number, like "#1"
                   // so don't make it clickable
               } else {
                   // set a link for when the user clicks on this word.
                   // it's not enough to use the word "hash", but you need the url scheme syntax "hash://"
                   // note:  since it's a URL now, the color is set to the project's tint color
                   attrString.addAttribute(NSLinkAttributeName, value: "hash:\(stringifiedWord)", range: matchRange)
               }
   
           }
       }
   
       // we're used to textView.text
       // but here we use textView.attributedText
       // again, this will also wipe out any fonts and colors from the storyboard,
       // so remember to re-add them in the attrs dictionary above
       self.attributedText = attrString
   }
   
   }
   

---

要使用它，您可以执行以下操作:

self.textView.text = "This is an #example test"
self.textView.resolveHashTags()

---

针对 Swift 4.0 更新:

extension UITextView {

    func resolveHashTags() {

        // turn string in to NSString
        let nsText = NSString(string: self.text)

        // this needs to be an array of NSString.  String does not work.
        let words = nsText.components(separatedBy: CharacterSet(charactersIn: "#ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_").inverted)

        // you can staple URLs onto attributed strings
        let attrString = NSMutableAttributedString()
        attrString.setAttributedString(self.attributedText)

        // tag each word if it has a hashtag
        for word in words {
            if word.count < 3 {
                continue
            }

            // found a word that is prepended by a hashtag!
            // homework for you: implement @mentions here too.
            if word.hasPrefix("#") {

                // a range is the character position, followed by how many characters are in the word.
                // we need this because we staple the "href" to this range.
                let matchRange:NSRange = nsText.range(of: word as String)

                // drop the hashtag
                let stringifiedWord = word.dropFirst()
                if let firstChar = stringifiedWord.unicodeScalars.first, NSCharacterSet.decimalDigits.contains(firstChar) {
                    // hashtag contains a number, like "#1"
                    // so don't make it clickable
                } else {
                    // set a link for when the user clicks on this word.
                    // it's not enough to use the word "hash", but you need the url scheme syntax "hash://"
                    // note:  since it's a URL now, the color is set to the project's tint color
                    attrString.addAttribute(NSAttributedStringKey.link, value: "hash:\(stringifiedWord)", range: matchRange)
                }

            }
        }

        // we're used to textView.text
        // but here we use textView.attributedText
        // again, this will also wipe out any fonts and colors from the storyboard,
        // so remember to re-add them in the attrs dictionary above
        self.attributedText = attrString
    }
}