表情符号支持NSAttributedString属性(紧排/段落样式)

我在UILabel上使用一个紧排属性来显示带有一些自定义字母间距的文本。不幸的是,在显示用户生成的字符串时,有时会看到如下情况:

即有时某些表情符号不显示

如果我注释掉字距,但应用一些段落样式,则会得到同样的错误呈现

我在文档中找不到任何明确拒绝支持特殊unicode字符的内容。我是做错了什么还是iOS错误

复制错误的代码可在此处作为游乐场使用: https://github.com/Bootstragram/Playgrounds/tree/master/LabelWithEmoji.playground

并抄录于此:

用于显示用户界面的基于UIKit的游乐场 导入UIKit 导入PlaygroundSupport 扩展NSAttribute字符串{ 静态func kernedSpacedText(\uText:String, 字母间距:CGFloat=0.0, 线宽:CGFloat?=无)—>NSAttribute字符串{ //TODO添加字体属性 让attributedString=NSMutableAttributedString(字符串:文本) attributedString。addAttribute(NSAttributedStringKey.kern, 值:字母间距, 范围:NSRange(位置:0,长度:text.count)) 如果let lineHeight=lineHeight{ 让paragraphStyle=NSMutableParagraphStyle() 段落样式。行距=线宽 attributedString。addAttribute(NSAttributedStringKey.paragraphStyle, 值:段落样式, 范围:NSRange(位置:0,长度:text.count)) } 返回AttributeString } } //对于UIFont中的familyName。familyNames家族{ //用于UIFont中的fontName。fontNames(用于familyName:familyName){ //打印(fontName) //} //} 类MyViewController:UIViewController{ 重写func loadView(){ let view=UIView() 看法背景颜色=。白色 让我来告诉你 let label=UILabel() 标签框架=CGRect(x:150,y:200,宽度:200,高度:100) 标签AttributeText=NSAttribute字符串。kernedSpacedText(myString) 标签numberOfLines=0 标签text颜色=。黑色 看法添加子视图(标签) 自己视图=视图 } } //在实时视图窗口中显示视图控制器 PlaygroundPage。现在的liveView=MyViewController()

谢谢

即有时某些表情符号不显示。

如果我注释掉字距,但应用一些段落样式,则会得到同样的错误呈现。

我在文档中找不到任何明确拒绝支持特殊unicode字符的内容。我是做错了什么还是iOS错误?

复制错误的代码可在此处作为游乐场使用: https://github.com/Bootstragram/Playgrounds/tree/master/LabelWithEmoji.playground

并复制到此处:

//: A UIKit based Playground for presenting user interface

import UIKit
import PlaygroundSupport

extension NSAttributedString {
    static func kernedSpacedText(_ text: String,
                                    letterSpacing: CGFloat = 0.0,
                                    lineHeight: CGFloat? = nil) -> NSAttributedString {
        // TODO add the font attribute

        let attributedString = NSMutableAttributedString(string: text)
        attributedString.addAttribute(NSAttributedStringKey.kern,
                                      value: letterSpacing,
                                      range: NSRange(location: 0, length: text.count))

        if let lineHeight = lineHeight {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.lineSpacing = lineHeight

            attributedString.addAttribute(NSAttributedStringKey.paragraphStyle,
                                          value: paragraphStyle,
                                          range: NSRange(location: 0, length: text.count))
        }

        return attributedString
    }
}

//for familyName in UIFont.familyNames {
//    for fontName in UIFont.fontNames(forFamilyName: familyName) {
//        print(fontName)
//    }
//}

class MyViewController : UIViewController {
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white

        let myString = "1⚽📺🍻⚾️🌯🏄‍♂️👍\n2 😀💿💸 🍻"

        let label = UILabel()
        label.frame = CGRect(x: 150, y: 200, width: 200, height: 100)
        label.attributedText = NSAttributedString.kernedSpacedText(myString)
        label.numberOfLines = 0
        label.textColor = .black

        view.addSubview(label)
        self.view = view
    }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()

谢谢