iOS UITextView 实现类似微博的话题、提及用户效果

func refreshTopicStyle() {
        
        let regex = try! NSRegularExpression(pattern: "此处填写正则表达式",
                                             options:[NSRegularExpression.Options.caseInsensitive])
        // 注意点
        let totalRange = NSMakeRange(0, (inputTextView.attributedText.string as NSString).length)
        let results = regex.matches(in: inputTextView.attributedText.string,
                                    options: NSRegularExpression.MatchingOptions.init(rawValue: 0),
                                    range: totalRange)
        let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: inputTextView.attributedText.string)
        attributedString.setAttributes(normalAttributes, range: totalRange)
        
        for result in results {
            attributedString.setAttributes(topicAttributes, range: result.range)
        }
        inputTextView.attributedText = attributedString
    }

let lengthA = inputTextView.textStorage.length
let lengthB = inputTextView.attributedText.string.utf16.count

inputTextView.addTapGesture(self, handler: #selector(tapAttributedText(tap:)))
@objc private func tapAttributedText(tap: UITapGestureRecognizer) {
    guard tap.isKind(of: UITapGestureRecognizer.self), let textView = tap.view as? UITextView else {
        return
    }
    let layoutManager = textView.layoutManager
    var tapLocation = tap.location(in: textView)
    tapLocation.x -= textView.textContainerInset.left
    tapLocation.y -= textView.textContainerInset.top
    let characterIndex = layoutManager.characterIndex(for: tapLocation,
                                                      in: textView.textContainer,
                                                      fractionOfDistanceBetweenInsertionPoints: nil)
    for result in getCheckResult(format: Constants.TopicRegularExpression, text: inputTextView.attributedText.string) {
        if result.range.location < characterIndex, characterIndex < result.range.location + result.range.length {
            // 此处响应点击事件
            MBProgressHUD.showOnlyText(to: self.view, title: "美好时光")
            return
        }
    }
    inputTextView.becomeFirstResponder()
}

/// 用来保存已选取用户信息的结构体
struct UserInfo {
    /// 用户名
    var userName: String
    /// 位置信息
    var range: NSRange
    /// 用于临时替换的等长字符串
    var placeholder: String
}

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    if text == "" {
        for (num, user) in usersArray.enumerated() { // usersArray 用于存放已选取的用户信息
            // ②删除选中的用户名
            if textView.selectedRange.location <= user.range.location && NSMaxRange(user.range) <= NSMaxRange(textView.selectedRange) {
                textView.replace(textView.selectedTextRange ?? UITextRange(), withText: "")
                return false
            }
            // ①选中用户名
            if textView.selectedRange.length == 0 && (textView.selectedRange.location == user.range.location + user.range.length) {
                textView.selectedRange = user.range
                return false
            }
        }
    }
}