在 iOS 中检测哈希标签 #、提及标签 @，就像在 Twitter 应用程序中一样

Question

我需要检测描述UILabel 中给出的#Tags 并将文本颜色更改为[UIColor BlueColor];，但我无法将UILabel 中的特定文本颜色更改为蓝色。现在我在自定义UITableViewCell 中使用这个UILabel。有没有办法解决这个问题，通过 Text Colors 区分 #Tags 和普通文本？谁能帮我解决这个问题？

Answer 1

-(NSMutableAttributedString*)decorateTags:(NSString *)stringWithTags{


    NSError *error = nil;

    //For "Vijay #Apple Dev"
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"#(\\w+)" options:0 error:&error];

    //For "Vijay @Apple Dev"
    //NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"@(\\w+)" options:0 error:&error];

    NSArray *matches = [regex matchesInString:stringWithTags options:0 range:NSMakeRange(0, stringWithTags.length)];
    NSMutableAttributedString *attString=[[NSMutableAttributedString alloc] initWithString:stringWithTags];

    NSInteger stringLength=[stringWithTags length];

    for (NSTextCheckingResult *match in matches) {

        NSRange wordRange = [match rangeAtIndex:1];

        NSString* word = [stringWithTags substringWithRange:wordRange];

        //Set Font
        UIFont *font=[UIFont fontWithName:@"Helvetica-Bold" size:15.0f];
        [attString addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, stringLength)];


        //Set Background Color
        UIColor *backgroundColor=[UIColor orangeColor];
        [attString addAttribute:NSBackgroundColorAttributeName value:backgroundColor range:wordRange];

        //Set Foreground Color
        UIColor *foregroundColor=[UIColor blueColor];
        [attString addAttribute:NSForegroundColorAttributeName value:foregroundColor range:wordRange];

        NSLog(@"Found tag %@", word);

    }

    // Set up your text field or label to show up the result

    //    yourTextField.attributedText = attString;
    //
    //    yourLabel.attributedText = attString;

    return attString;
}

Answer 2

新： 在 iOS 9 中使用此链接https://github.com/hsusmita/ResponsiveLabel

旧： 使用它也可以自定义https://github.com/SebastienThiebaud/STTweetLabel

Answer 3

这是一个 Swift 解决方案。它使用UITextView，它支持属性文本、多行，并支持内置委托将点击事件映射到选定的单词（用户在看到蓝色文本时可能会期望）。

它没有将字符范围更改为.blueColor()，而是添加了一个链接属性，该属性会自动将可点击文本设置为您的全局色调。

它还包含对 Twitter 主题标签规则的一些基本支持，用于处理数字 #1 和特殊字符 @abc.go。

工作示例项目：

https://github.com/ThornTechPublic/SwiftTextViewHashtag/blob/master/textViewSample/UITextField%2BExtension.swift

具有更通用解释的博文：

http://www.thorntech.com/2015/06/detecting-hashtags-mentions-and-urls-with-swift/

extension UITextView {

    func chopOffNonAlphaNumericCharacters(text:String) -> String {
        var nonAlphaNumericCharacters = NSCharacterSet.alphanumericCharacterSet().invertedSet
        let characterArray = text.componentsSeparatedByCharactersInSet(nonAlphaNumericCharacters)
        return characterArray[0]
    }

    /// Call this manually if you want to hash tagify your string.
    func resolveHashTags(){

        let schemeMap = [
            "#":"hash",
            "@":"mention"
        ]

        // Turn string in to NSString.
        // NSString gives us some helpful API methods
        let nsText:NSString = self.text

        // Separate the string into individual words.
        // Whitespace is used as the word boundary.
        // You might see word boundaries at special characters, like before a period.
        // But we need to be careful to retain the # or @ characters.
        let words:[NSString] = nsText.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()) as! [NSString]

        // Attributed text overrides anything set in the Storyboard.
        // So remember to set your font, color, and size here.
        var attrs = [
//            NSFontAttributeName : UIFont(name: "Georgia", size: 20.0)!,
//            NSForegroundColorAttributeName : UIColor.greenColor(),
            NSFontAttributeName : UIFont.systemFontOfSize(17.0)
        ]

        // Use an Attributed String to hold the text and fonts from above.
        // We'll also append to this object some hashtag URLs for specific word ranges.
        var attrString = NSMutableAttributedString(string: nsText as String, attributes:attrs)

        // Iterate over each word.
        // So far each word will look like:
        // - I
        // - visited
        // - #123abc.go!
        // The last word is a hashtag of #123abc
        // Use the following hashtag rules:
        // - Include the hashtag # in the URL
        // - Only include alphanumeric characters.  Special chars and anything after are chopped off.
        // - Hashtags can start with numbers.  But the whole thing can't be a number (#123abc is ok, #123 is not)
        for word in words {

            var scheme:String? = nil

            if word.hasPrefix("#") {
                scheme = schemeMap["#"]
            } else if word.hasPrefix("@") {
                scheme = schemeMap["@"]
            }

            // found a word that is prepended by a hashtag
            if let scheme = scheme {

                // convert the word from NSString to String
                // this allows us to call "dropFirst" to remove the hashtag
                var stringifiedWord:String = word as String

                // example: #123abc.go!

                // drop the hashtag
                // example becomes: 123abc.go!
                stringifiedWord = dropFirst(stringifiedWord)

                // Chop off special characters and anything after them.
                // example becomes: 123abc
                stringifiedWord = chopOffNonAlphaNumericCharacters(stringifiedWord)

                if let stringIsNumeric = stringifiedWord.toInt() {
                    // don't convert to hashtag if the entire string is numeric.
                    // example: 123abc is a hashtag
                    // example: 123 is not
                } else if stringifiedWord.isEmpty {
                    // do nothing.
                    // the word was just the hashtag by itself.
                } else {
                    // set a link for when the user clicks on this word.
                    var matchRange:NSRange = nsText.rangeOfString(stringifiedWord as String)
                    // Remember, we chopped off the hash tag, so:
                    // 1.) shift this left by one character.  example becomes:  #123ab
                    matchRange.location--
                    // 2.) and lengthen the range by one character too.  example becomes:  #123abc
                    matchRange.length++
                    // URL syntax is http://123abc

                    // Replace custom scheme with something like hash://123abc
                    // URLs actually don't need the forward slashes, so it becomes hash:123abc
                    // Custom scheme for @mentions looks like mention:123abc
                    // As with any URL, the string will have a blue color and is clickable
                    attrString.addAttribute(NSLinkAttributeName, value: "\(scheme):\(stringifiedWord)", range: matchRange)
                }
            }

        }

        // Use textView.attributedText instead of textView.text
        self.attributedText = attrString
    }

}

用法：

textView.resolveHashTags()

处理点击事件：

func showHashTagAlert(tagType:String, payload:String){
    let alertView = UIAlertView()
    alertView.title = "\(tagType) tag detected"
    // get a handle on the payload
    alertView.message = "\(payload)"
    alertView.addButtonWithTitle("Ok")
    alertView.show()
}

extension ViewController : UITextViewDelegate {

    func textView(textView: UITextView, shouldInteractWithURL URL: NSURL, inRange characterRange: NSRange) -> Bool {

        // check for our fake URL scheme hash:helloWorld
        if let scheme = URL.scheme {
            switch scheme {
            case "hash" :
                showHashTagAlert("hash", payload: URL.resourceSpecifier!)
            case "mention" :
                showHashTagAlert("mention", payload: URL.resourceSpecifier!)
            default:
                println("just a regular url")
            }
        }

        return true
    }

}

Answer 4

你可以使用https://github.com/Krelborn/KILabel这个库。它还检测用户对主题标签的点击 像这样：

label.hashtagLinkTapHandler = ^(KILabel *label, NSString *string, NSRange range) {
  NSLog(@"Hashtag tapped %@", string);
};