自定义NSAttributedString(iOS7 +)中的下划线模式 [英] Customize underline pattern in NSAttributedString (iOS7+)

问题描述

我正在尝试将虚线下划线样式添加到NSAttributedString(在iOS7 +/TextKit上).当然，我尝试了内置的NSUnderlinePatternDot:

I'm trying to add a dotted underline style to an NSAttributedString (on iOS7+/TextKit). Of course, I tried the built-in NSUnderlinePatternDot:

NSString *string = self.label.text;
NSRange underlineRange = [string rangeOfString:@"consetetur sadipscing elitr"];

NSMutableAttributedString *attString = [[NSMutableAttributedString alloc] initWithString:string];
[attString addAttributes:@{NSUnderlineStyleAttributeName: @(NSUnderlineStyleSingle | NSUnderlinePatternDot)} range:underlineRange];

self.label.attributedText = attString;

但是，由此产生的样式实际上是虚线而不是虚线:

However, the style produced by this is actually rather dashed than dotted:

我在这里缺少明显的东西(NSUnderlinePatternReallyDotted?;))还是有可能自定义线点图案?

Am I missing something obvious here (NSUnderlinePatternReallyDotted? ;) ) or is there perhaps a way to customize the line-dot-pattern?

推荐答案

根据Eiko& Dave的回答，

According to Eiko&Dave's answer, i made an example like this

我尝试通过使用UILabel而不是UITextView来完成此操作，但是从stackoverflow或其他网站搜索后找不到解决方案.因此，我使用UITextView来做到这一点.

i've try to finish that by using UILabel rather than UITextView, but could not find a solution after searching from stackoverflow or other websites. So, i used UITextView to do that.

    let storage = NSTextStorage()
    let layout = UnderlineLayout()
    storage.addLayoutManager(layout)
    let container = NSTextContainer()
    container.widthTracksTextView = true
    container.lineFragmentPadding = 0
    container.maximumNumberOfLines = 2
    container.lineBreakMode = .byTruncatingTail
    layout.addTextContainer(container)

    let textView = UITextView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width-40, height: 50), textContainer: container)
    textView.isUserInteractionEnabled = true
    textView.isEditable = false
    textView.textContainerInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
    textView.text = "1sadasdasdasdasdsadasdfdsf"
    textView.backgroundColor = UIColor.white

    let rg = NSString(string: textView.text!).range(of: textView.text!)
    let attributes = [NSAttributedString.Key.underlineStyle.rawValue: 0x11,
                      NSAttributedString.Key.underlineColor: UIColor.blue.withAlphaComponent(0.2),
                      NSAttributedString.Key.foregroundColor: UIColor.black, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17),
                      NSAttributedString.Key.baselineOffset:10] as! [NSAttributedString.Key : Any]

    storage.addAttributes(attributes, range: rg)
    view.addSubview(textView)

覆盖LayoutManage方法

override LayoutManage Method

class UnderlineLayout: NSLayoutManager {
    override func drawUnderline(forGlyphRange glyphRange: NSRange, underlineType underlineVal: NSUnderlineStyle, baselineOffset: CGFloat, lineFragmentRect lineRect: CGRect, lineFragmentGlyphRange lineGlyphRange: NSRange, containerOrigin: CGPoint) {
    if let container = textContainer(forGlyphAt: glyphRange.location, effectiveRange: nil) {
        let boundingRect = self.boundingRect(forGlyphRange: glyphRange, in: container)
        let offsetRect = boundingRect.offsetBy(dx: containerOrigin.x, dy: containerOrigin.y)

        let left = offsetRect.minX
        let bottom = offsetRect.maxY-15
        let width = offsetRect.width
        let path = UIBezierPath()
        path.lineWidth = 3
        path.move(to: CGPoint(x: left, y: bottom))
        path.addLine(to: CGPoint(x: left + width, y: bottom))
        path.stroke()
    }
}

在我的解决方案中，我必须通过使用NSAttributedString属性NSMutableParagraphStyle().lineSpacing扩展lineSpacing并保留自定义下划线，但似乎没有用，但NSAttributedString.Key.baselineOffset可以使用.希望可以

in my solution, i've to expand lineSpacing also keep a customize underline by using NSAttributedString property NSMutableParagraphStyle().lineSpacing, but it seems that didn't work, but NSAttributedString.Key.baselineOffset is worked. hope can

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