CoreText

• 變態(tài)需求要根據(jù)屏幕寬度谈秫，first name長(zhǎng)度不確定

1. first name較短
   1. 若 Good morning, first name,1行能顯示下， 用 Good morning, first name
   2. 若 Good morning, first name,1行不能顯示下：若Hi, first name 能顯示下鱼鼓，則用Hi否則考慮兩行的情況拟烫。
      兩行情況同上，但是換行的時(shí)候得在第一行的末尾加 -
2. first name特別長(zhǎng)
   1. 用Hi,且末尾得加上 ...

• 先上代碼吧

        // 1.初始化路徑
        let path = CGPath(rect: self.bounds, transform: nil)
        // 2.初始化framesetter
        let framesetter = CTFramesetterCreateWithAttributedString(text)
        
        // 3.繪制frame
        let frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, text.length), path, nil)
        self.ctframe = frame
    
        // 獲得CTLine數(shù)組
        let lines = CTFrameGetLines(frame)
        
        // 獲得行數(shù)
        let numberOfLines = CFArrayGetCount(lines)
        
        // 獲得每一行的origin, CoreText的origin是在字形的baseLine處的
        var lineOrigins = [CGPoint](repeating: CGPoint(x: 0, y: 0), count: numberOfLines)
        CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), &lineOrigins)
        
        // 遍歷每一行
        for index in 0..<numberOfLines {
            let origin = lineOrigins[index]
            let line = unsafeBitCast(CFArrayGetValueAtIndex(lines, index), to: CTLine.self)
            let lineRef: CTLine = line
            let lineRange: CFRange = CTLineGetStringRange(lineRef)
            let range: NSRange = NSMakeRange(lineRange.location, lineRange.length)
            let lineString = (attributedText?.attributedSubstring(from: range)).string
        }

這樣就得到了每一行的characters
重要的是這個(gè)是利用CoreText 的富文本屬性去做的迄本，一定要是這個(gè)Label的NSMutableAttributedString, 然后把得到的string轉(zhuǎn)成 AttributedString硕淑，給label的富文本屬性，這樣才正確嘉赎。

• 富文本屬性簡(jiǎn)單用法舉例：

        let font = UIFont.boldSystemFont(ofSize: 20)
    
        let attributedText = NSMutableAttributedString(string: content)
        // 字體顏色
        attributedText.addAttribute(NSForegroundColorAttributeName, value: UIColor.red, range: NSMakeRange(0, attributedText.length))
        // 字體
        attributedText.addAttribute(NSFontAttributeName, value: font, range: NSMakeRange(0, attributedText.length))
        // 段落樣式
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .center
        paragraphStyle.lineBreakMode = .byCharWrapping
        // 行間距
        paragraphStyle.lineSpacing = 5.0
        // 字符間距
        paragraphStyle.paragraphSpacing = 2.0
        attributedText.addAttribute(NSParagraphStyleAttributeName, value: paragraphStyle, range: NSRange(location: 0, length: attributedText.length))
        label.attributedText = attributedText