简介：

Core Text主要用来对文本进行排版布局和字体处理，与其他UI组件相比，由于它直接与Quartz交互，因此排版效率高，渲染速度快。

下图是Core Text的架构图：

富文本实现：（GitHub传送门）

接下来我们通过一个例子来看看如何实现富文本展示。我们按职责将功能拆分成几个类来完成，

1.一个显示的类，CTDisplayView，仅负责显示。

import UIKit

class CTDisplayView: UIView {

    /*
    // Only override draw() if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func draw(_ rect: CGRect) {
        // Drawing code
    }
    */
    var data:CoreTextData?
    
    override func draw(_ rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()
        
        //翻转坐标系
        context?.textMatrix = CGAffineTransform.identity
        context?.translateBy(x: 0, y: self.bounds.size.height)
        context?.scaleBy(x: 1, y: -1)
        
        if data != nil {
            CTFrameDraw((self.data?.ctFrame)!, context!)
        }
    }

}

 

2.一个配置类，CTFrameParserConfig，负责配置一些默认的参数。

import UIKit

class CTFrameParserConfig: NSObject {
    var width:CGFloat = 200.0
    var fontName: NSString = "PingFangSC-Regular"
    var fontSize: CGFloat = 17.0
    var lineSpace: CGFloat = 0.0
    var textColor = ColorRGBA(r: 0, g: 0, b: 0, a: 1)
}

 

3.一个排版类，CTFrameParser，负责实现内容的排版。

class CTFrameParser: NSObject {
    
    // MARK: ------处理模板文件并返回数据源------
    class func parserTemplateFlie(_ path: NSString, config: CTFrameParserConfig) -> CoreTextData {
        let content = self.loadTemplateFile(path, config: config)
        return self.parserAttributedContent(content, config: config)
    }
    
    // MARK: ------加载模板文件------
    class func loadTemplateFile(_ path: NSString, config: CTFrameParserConfig) -> NSAttributedString {
        let data = NSData(contentsOfFile: path as String)
        let result = NSMutableAttributedString()
        if (data != nil) {
            let array:NSArray = try! JSONSerialization.jsonObject(with: data! as Data, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSArray
            if array.isKind(of: NSArray.self) {
                for dic in array {
                    if let dict = dic as? NSDictionary {
                        let type = dict["type"]
                        if ((type as! NSString).isEqual(to:"txt")) {
                            let attributedStr = self.parserAttributedContentConvert(dict, config: config)
                            result.append(attributedStr)
                        }
                    }
                }
            }
        }
        return result
    }
    
    // MARK: ------设置文字模板描述------
    class func parserAttributedContentConvert(_ dict: NSDictionary, config: CTFrameParserConfig) -> NSAttributedString {
        let attributes:NSMutableDictionary = self.attributes(config) as! NSMutableDictionary
        
        //colorConvert
        let colorStr = (dict["color"]) as? String
        if (colorStr != nil && colorStr != "default") {
            let hexValue = Int(strtoul(colorStr, nil, 16))
            let color = ColorHEX(hexValue: hexValue)
            attributes.setObject(color, forKey: kCTForegroundColorAttributeName as! NSCopying)
        }
        
        //fontConvert
        var fontName = dict["fontName"] as? String
        var fontSize = dict["fontSize"] as? CGFloat
        if (fontName == nil || fontName == "default") {
           fontName = config.fontName as String
        }
        if (fontSize == nil || fontSize! <= 0) {
           fontSize = config.fontSize
        }
        let font = CTFontCreateWithName(fontName as CFString?, fontSize!, nil)
        attributes.setObject(font, forKey: kCTFontAttributeName as! NSCopying)
    
        let content = dict["content"] as! NSString
        
        return NSAttributedString(string: content as String, attributes: attributes.copy() as? [String : Any])
    }

    // MARK: ------设置初始化描述------
    class func attributes(_ config: CTFrameP