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<NSAttributedStringKey,Any>!
}
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<NSAttributedStringKey,Any>?,linkArr:Array<LinkAttributesModel>) {
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..<lineCount {
let line = lines[i]//CFArrayGetValueAtIndex(lines, i) as! CTLine
var ascent:CGFloat = 0
var descent:CGFloat = 0
var leading:CGFloat = 0
let width = CGFloat(CTLineGetTypographicBounds(line, &ascent, &descent, &leading))
let height = ascent + abs(descent) + leading
var rect = CGRect(x: pt.x, y: pt.y, width, height: height)
// var rect = flippedRect.applying(flipTransform)
var lineSpace:CGFloat = 0;
if let style = tmpAttributedString?.attribute(NSAttributedStringKey.paragraphStyle, at: 0, effectiveRange: nil) as? NSParagraphStyle{
lineSpace = style.lineSpacing
}
rect.origin.y = (height+lineSpace)*CGFloat(i);
if rect.contains(pt) {
var stringIndex = CTLineGetStringIndexForPosition(line, pt)
var offset:CGFloat = 0
CTLineGetOffsetForStringIndex(line, stringIndex, &offset)
if (offset > 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<String,Any> = ["height":100,"width":200]
let imageDataPointer = UnsafeMutablePointer<Dictionary<String,Any>>.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
")
let suffixStr = createAttributedString(str: "
haha 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<CGPoint> = Array(repeating: .zero, count: lines.count)
CTFrameGetLineOrigins(frame, CFRange(location: 0, length: 0), &lineOrigins)
for i in 0..<lines.count {
let line = lines[i] as! CTLine
let runs = CTLineGetGlyphRuns(line) as Array
print("lineCount == (lines.count) i == (i)
")
for j in 0..<runs.count {
let run = runs[j] as! CTRun
let runAttribute = CTRunGetAttributes(run) as NSDictionary
// if runAttribute == nil {return}
print("runCount == (runs.count) j == (j) runattribute == (runAttribute)")
let runDelegate = runAttribute.object(forKey: kCTRunDelegateAttributeName as String)
if (runDelegate == nil) {continue}
var ascent:CGFloat = 0
var descent:CGFloat = 0
let CGFloat = CGFloat(CTRunGetTypographicBounds(run, CFRange(location: 0, length: 0), &ascent, &descent, nil))
let xoffset = lineOrigins[i].x + CTLineGetOffsetForStringIndex(line, CTRunGetStringRange(run).location, nil)
let yoffset = lineOrigins[i].y
let drawRect = CGRect(x: xoffset, y: yoffset, width, height: ascent+descent)
if let imgName = runAttribute.object(forKey: "imageName") as? String {
let img = UIImage(named: imgName)
ctx.draw((img?.cgImage)!, in: drawRect)
}
}
}
}
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")