最近在開發(fā)中，遇到一個奇怪的問題，就是當(dāng)顯示一串文本，當(dāng)文本最后一個字符是Emoji時，Emoji顯示亂碼，如圖：

錯誤展示

正確展示應(yīng)該是這樣的

正確展示

而展示邏輯也很簡單，一個UILabel控件通過attributedText展示

signLabel.attributedText = user.introductionAttribute

如果用label.text展示的話，則是正常的

signLabel.text= user.introduction

直接說問題點和解決方案：

    var introductionAttribute: NSAttributedString {
        let attributedString = NSMutableAttributedString(string: introduction,
                                                         attributes: [.font: YRUserHeaderLayoutable.introFont])
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.paragraphSpacing = 0
        paragraphStyle.firstLineHeadIndent = 0
        paragraphStyle.headIndent = 0
        paragraphStyle.paragraphSpacingBefore = 0
        attributedString.addAttribute(NSAttributedString.Key.paragraphStyle, value: paragraphStyle, range: NSRange(location: 0, length: introduction.count))
        return attributedString
    }

問題出在了最后一行代碼

 attributedString.addAttribute(NSAttributedString.Key.paragraphStyle, value: paragraphStyle, range: NSRange(location: 0, length: introduction.count))

在計算字符串長度時， Swift計算的是

/// The number of characters in a string.
 public var count: Int { get }

let swiftCount = introduction.count
let ocLength = (introduction as NSString).length
print("introducetion:\(introduction)")
print("swiftCount:\(swiftCount)")
print("ocLength:\(ocLength)")

打印：

introducetion:這是一個emoji??
swiftCount:10
ocLength:11

當(dāng)用Swift.count計算長度時出錯，修復(fù)也很簡單，

attributedString.addAttribute(NSAttributedString.Key.paragraphStyle, value: paragraphStyle, range: NSRange(location: 0, length: (introduction as NSString).length))