相对于UIKit，使用coretext绘制文本效率高，具有更高的自由度，可随时插入图片，增加文本点击事件等。

1.增加文本的点击事件

思路：定义UILabel子类，设置可点击的富文本range及其他属性（颜色、字体），touchBegin方法中根据点击位置判断所在行所在index，最后判断index是否在range内，若在，则响应事件。

　　首先定义可点击的文本model，该model主要含有3个属性，string-用于回调显示，range-用于判断位置，attributes-用于绘制文本

class LinkAttributesModel:NSObject {    var string:String!    var range:NSRange!    var attributes:Dictionary
     
      !}
     

 　　接着在label子类实现方法setString(string:String,attributes:Dictionary<NSAttributedStringKey,Any>?,linkArr:Array<LinkAttributesModel>)，第一个参数是显示string，第二个参数是string的属性，第三个参数是一个可点击文本的集合，需要手动赋值

// 声明func setString(string:String,attributes:Dictionary
     
      ?,linkArr:Array
      
       ) {        locLinkArr = linkArr;        let attributedString = NSMutableAttributedString(string: string, attributes: attributes)        for linkMdl in linkArr {            attributedString.addAttributes(linkMdl.attributes, range: linkMdl.range)        }//        self.attributedText = attributedString        tmpAttributedString = attributedString                // create frameRef        let frameSetter = CTFramesetterCreateWithAttributedString(attributedString)        let path = CGMutablePath()        path.addRect(self.bounds)        frameRef = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, string.count), path, nil)                self.isUserInteractionEnabled = true    }// 调用// 构造属性model        var mdlArr = [LinkAttributesModel]()        for i in 0...2 {            let mdl = LinkAttributesModel()            let loc = i*10            let range = NSMakeRange(loc, 5)            mdl.range = range            let startIdx = showString.index(showString.startIndex, offsetBy: range.location)            let endIdx = showString.index(startIdx, offsetBy: range.length)            mdl.string = String(showString[startIdx...endIdx])            let randomColor = UIColor(red: CGFloat(arc4random_uniform(256))/255.0, green: CGFloat(arc4random_uniform(256))/255.0, blue: CGFloat(arc4random_uniform(256))/255.0, alpha: 1)            mdl.attributes = [NSAttributedStringKey.foregroundColor:randomColor]            mdlArr.append(mdl)        }                let lbl = Taplabel(frame:self.view.bounds.insetBy(dx: 0, dy: 50))        let style = NSMutableParagraphStyle()        style.lineSpacing = 10        lbl.setString(string: showString, attributes: [NSAttributedStringKey.font:UIFont.systemFont(ofSize: 20),NSAttributedStringKey.paragraphStyle:style], linkArr: mdlArr)
      
     

 　　最后根据属性文本创建对应的frameRef，然后遍历其CTLine数组，判断点击的位置在哪行内，再根据x获取当前行的偏移位置index，最后遍历linkAttributesModel，判断range是否包含index，如果包含，则触发回调事件

func touchEvents(pt:CGPoint) {        if (frameRef == nil) {return}        let lines:[CTLine] = CTFrameGetLines(frameRef!) as! [CTLine]        let lineCount = lines.count        if (lineCount == 0) {return}//        let flipTransform = CGAffineTransform(translationX: 0, y: self.bounds.size.height).scaledBy(x: 1, y: -1)        for i in 0..
     
       pt.x) {                    stringIndex = stringIndex - 1                }                                for linkMdl in locLinkArr! {                    if linkMdl.range.contains(stringIndex) {                        tapBlock!(linkMdl.string)                    }                }            }        }    }
     

 　　上述代码的主要核心在于

　　 a.算行高　　CTLineGetTypographicBounds(line,&asent,&descent,&leading)

　　 b.算行内偏移　　CTLineGetStringIndexForPosition(line,pt)　　如果根据该index算出的偏移量大于pt.x，则index-1

　　 c.判断range包含　　range.contains(index)

 

2.图文绘制

思路：NSAttributedString中插入占位空白符-关联图片属性。图片宽高由CTRunDelegate，图片可藏于追加属性中。ctx.draw(image,in:drawRect)时遍历CTLine，寻找含有CTRunDelegate的CTRun，如果存在，则获取图片的相应数组，构造drawRect和image绘制图片。

　　追加图片属性

func appendImage(attrStr:NSAttributedString)->NSAttributedString {        var callBacks = CTRunDelegateCallbacks(version: kCTRunDelegateVersion1, dealloc: { (pointer) in        }, getAscent: { (ref) -> CGFloat in            let dic = ref.assumingMemoryBound(to: NSDictionary.self)            return dic.pointee.object(forKey: "height") as! CGFloat        }, getDescent: { (ref) -> CGFloat in            return 0        }) { (ref) -> CGFloat in            let dic = ref.assumingMemoryBound(to: NSDictionary.self)            return dic.pointee.object(forKey: "width") as! CGFloat        }                let imageData:Dictionary
     
       = ["height":100,"width":200]        let imageDataPointer = UnsafeMutablePointer
      
       
        >.allocate(capacity: 1)        imageDataPointer.initialize(to: imageData)        let runDelegate = CTRunDelegateCreate(&callBacks, imageDataPointer)                let runAttributes:[NSAttributedStringKey:Any] = [kCTRunDelegateAttributeName as NSAttributedStringKey:runDelegate as Any]        let runAttributeStr = NSMutableAttributedString(string: " ", attributes: runAttributes)        runAttributeStr.addAttribute(NSAttributedStringKey(rawValue: "imageName"), value: "shot", range: NSMakeRange(0, 1))                let mutableAttrStr = NSMutableAttributedString(attributedString: attrStr)        let whiteSpaceStr = createAttributedString(str: "临时换行\n")        let suffixStr = createAttributedString(str: "\nhaha insert image succeed")        mutableAttrStr.append(whiteSpaceStr)        mutableAttrStr.append(runAttributeStr)        mutableAttrStr.append(suffixStr)        return mutableAttrStr    }
       
      
     

 　　绘制追加的图片属性

func drawImage(frame:CTFrame,ctx:CGContext) {        let lines = CTFrameGetLines(frame) as Array        var lineOrigins:Array
     
       = Array(repeating: .zero, count: lines.count)        CTFrameGetLineOrigins(frame, CFRange(location: 0, length: 0), &lineOrigins)        for i in 0..
     

 　　关键代码是

　　a.获取lineOrigin　　CTFrameGetLineOrigins(frame, CFRange(location: 0, length: 0), &lineOrigins)

　　b.获取width,height　　CTRunGetTypographicBounds(run, CFRange(location: 0, length: 0), &ascent, &descent, nil)　　//图片忽略leading属性

　　c.获取x偏移量　　lineOrigins[i].x+CTLineGetOffsetForStringIndex(line,CTRunGetStringRange(run).location,nil)

　　d.获取图片　　runAttributes.object(forKey:"imageName")