背景色和圆角

我通过检查文本片段的框架来做到这一点。在我的项目中，我需要在用户输入文本时突出显示标签。

class HashtagTextView: UITextView {


let hashtagRegex = "#[-_0-9A-Za-z]+"


private var cachedFrames: [CGRect] = []


private var backgrounds: [UIView] = []


override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
configureView()
}


required init?(coder: NSCoder) {
super.init(coder: coder)
configureView()
}


override func layoutSubviews() {
super.layoutSubviews()


// Redraw highlighted parts if frame is changed
textUpdated()
}


deinit {
NotificationCenter.default.removeObserver(self)
}


@objc private func textUpdated() {
// You can provide whatever ranges needed to be highlighted
let ranges = resolveHighlightedRanges()


let frames = ranges.compactMap { frame(ofRange: $0) }.reduce([], +)


if cachedFrames != frames {
cachedFrames = frames


backgrounds.forEach { $0.removeFromSuperview() }
backgrounds = cachedFrames.map { frame in
let background = UIView()
background.backgroundColor = UIColor.hashtagBackground
background.frame = frame
background.layer.cornerRadius = 5
insertSubview(background, at: 0)
return background
}
}
}


/// General setup
private func configureView() {
NotificationCenter.default.addObserver(self, selector: #selector(textUpdated), name: UITextView.textDidChangeNotification, object: self)
}


/// Looks for locations of the string to be highlighted.
/// The current case - ranges of hashtags.
private func resolveHighlightedRanges() -> [NSRange] {
guard text != nil, let regex = try? NSRegularExpression(pattern: hashtagRegex, options: []) else { return [] }


let matches = regex.matches(in: text, options: [], range: NSRange(text.startIndex..<text.endIndex, in: text))
let ranges = matches.map { $0.range }
return ranges
}
}

还有一个辅助扩展，用于确定范围框架:

extension UITextView {
func convertRange(_ range: NSRange) -> UITextRange? {
let beginning = beginningOfDocument
if let start = position(from: beginning, offset: range.location), let end = position(from: start, offset: range.length) {
let resultRange = textRange(from: start, to: end)
return resultRange
} else {
return nil
}
}


func frame(ofRange range: NSRange) -> [CGRect]? {
if let textRange = convertRange(range) {
let rects = selectionRects(for: textRange)
return rects.map { $0.rect }
} else {
return nil
}
}
}

结果文本视图:

只需定制 NSLayoutManager并覆盖 drawUnderline(forGlyphRange:underlineType:baselineOffset:lineFragmentRect:lineFragmentGlyphRange:containerOrigin:) 苹果 API 文件

在此方法中，您可以自己绘制下划线,

override func drawUnderline(forGlyphRange glyphRange: NSRange,
underlineType underlineVal: NSUnderlineStyle,
baselineOffset: CGFloat,
lineFragmentRect lineRect: CGRect,
lineFragmentGlyphRange lineGlyphRange: NSRange,
containerOrigin: CGPoint
) {
let firstPosition  = location(forGlyphAt: glyphRange.location).x


let lastPosition: CGFloat


if NSMaxRange(glyphRange) < NSMaxRange(lineGlyphRange) {
lastPosition = location(forGlyphAt: NSMaxRange(glyphRange)).x
} else {
lastPosition = lineFragmentUsedRect(
forGlyphAt: NSMaxRange(glyphRange) - 1,
effectiveRange: nil).size.width
}


var lineRect = lineRect
let height = lineRect.size.height * 3.5 / 4.0 // replace your under line height
lineRect.origin.x += firstPosition
lineRect.size.width = lastPosition - firstPosition
lineRect.size.height = height


lineRect.origin.x += containerOrigin.x
lineRect.origin.y += containerOrigin.y


lineRect = lineRect.integral.insetBy(dx: 0.5, dy: 0.5)


let path = UIBezierPath(rect: lineRect)
// let path = UIBezierPath(roundedRect: lineRect, cornerRadius: 3)
// set your cornerRadius
path.fill()
}

然后构建您的 NSAttributedString并添加属性 .underlineStyle和 .underlineColor。

addAttributes(
[
.foregroundColor: UIColor.white,
.underlineStyle: NSUnderlineStyle.single.rawValue,
.underlineColor: UIColor(red: 51 / 255.0, green: 154 / 255.0, blue: 1.0, alpha: 1.0)
],
range: range
)

就是这样！

我在@codeBearer 的回答后面写了下面的代码。

import UIKit


class CustomAttributedTextView: UITextView {


override func layoutSubviews() {
super.layoutSubviews()
}


func clearForReuse() {
setNeedsDisplay()
}
var lineCountUpdate: ((Bool) -> Void)?


override func draw(_ rect: CGRect) {
super.draw(rect)
UIColor.clear.setFill()
UIColor.clear.setFill()
guard let context = UIGraphicsGetCurrentContext() else { return }
context.textMatrix = .identity
context.translateBy(x: 0, y: bounds.size.height)
context.scaleBy(x: 1.0, y: -1.0)
let path = CGMutablePath()
let size = sizeThatFits(CGSize(width: self.frame.width, height: .greatestFiniteMagnitude))
path.addRect(CGRect(x: 0, y: 0, width: size.width, height: size.height), transform: .identity)


let framesetter = CTFramesetterCreateWithAttributedString(attributedText as CFAttributedString)
let frame: CTFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, attributedText.length), path, nil)


let lines: [CTLine] = frame.lines


var origins = [CGPoint](repeating: .zero, count: lines.count)
CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), &origins)


for lineIndex in 0..<lines.count {
let line = lines[lineIndex]
let runs: [CTRun] = line.ctruns
var tagCountInOneLine = 0
for run in runs {
var cornerRadius: CGFloat = 3
let attributes: NSDictionary = CTRunGetAttributes(run)
var imgBounds: CGRect = .zero
if let value: UIColor =  attributes.value(forKey: NSAttributedString.Key.customBackgroundColor.rawValue) as? UIColor {
var ascent: CGFloat = 0
imgBounds.size.width = CGFloat(CTRunGetTypographicBounds(run, CFRangeMake(0, 0), &ascent, nil, nil) + 4)
imgBounds.size.height = ascent + 6


let xOffset = CTLineGetOffsetForStringIndex(line, CTRunGetStringRange(run).location, nil)
imgBounds.origin.x = origins[lineIndex].x + xOffset + 3
imgBounds.origin.y = origins[lineIndex].y - 13


if lineIndex != 0 {
imgBounds.origin.y = imgBounds.origin.y - 1
}


let path = UIBezierPath(roundedRect: imgBounds, cornerRadius: cornerRadius)
value.setFill()
path.fill()
value.setStroke()
}
}
}
}
}


extension CTFrame {


var lines: [CTLine] {
let linesAO: [AnyObject] = CTFrameGetLines(self) as [AnyObject]
guard let lines = linesAO as? [CTLine] else {
return []
}


return lines
}
}


extension CTLine {
var ctruns: [CTRun] {
let linesAO: [AnyObject] = CTLineGetGlyphRuns(self) as [AnyObject]
guard let lines = linesAO as? [CTRun] else {
return []
}


return lines
}
}