NSAttributedString项目符号列表问题

NSAttributedString bullet list issues(NSAttributedString项目符号列表问题)

问题描述

我正在尝试使用NSAttributedString和UITextView创建项目符号列表。以下是我到目前为止所能做到的：

可以看到，两行之间有一个小的"移位"。下面是我用来构建属性字符串的一段代码：

func add(bulletList strings: [String],
         indentation: CGFloat = 15,
         lineSpacing: CGFloat = 3,
         paragraphSpacing: CGFloat = 10) {

    func createParagraphAttirbute() -> NSParagraphStyle {
        var paragraphStyle: NSMutableParagraphStyle
        let nonOptions = NSDictionary() as! [NSTextTab.OptionKey: Any]

        paragraphStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
        paragraphStyle.tabStops = [
            NSTextTab(textAlignment: .left, location: indentation, options: nonOptions)]
        paragraphStyle.defaultTabInterval = indentation
        paragraphStyle.firstLineHeadIndent = 0
        paragraphStyle.lineSpacing = lineSpacing
        paragraphStyle.paragraphSpacing = paragraphSpacing
        paragraphStyle.headIndent = indentation
        return paragraphStyle
    }

    var buffer = NSMutableAttributedString.init()

    for string in strings {
        let formattedString = "u{2022} (string)
"
        let attributedString = NSMutableAttributedString(string: formattedString)
        let paragraphStyle = createParagraphAttirbute()

        attributedString.addAttributes(
            [NSAttributedStringKey.paragraphStyle : paragraphStyle],
            range: NSMakeRange(0, attributedString.length))

        attributedString.addAttributes(
            textAttributes,
            range: NSMakeRange(0, attributedString.length))

        let string:NSString = NSString(string: formattedString)
        let rangeForBullet:NSRange = string.range(of: bulletPoint)
        attributedString.addAttributes(bulletAttirbutes, range: rangeForBullet)
        buffer.append(attributedString)
    }
}

您认为所选段落参数是否有问题？因为代码执行的几乎是预期的操作(不包括此差距)。

更新%1

遵循@the4kman建议，我更改了提供的代码，如下所示：

paragraphStyle.firstLineHeadIndent = indentation

但现在我将所有行彼此对齐，包括项目符号：

更新2

好的，解决方案非常简单-用制表符替换空格。请参阅下面更新的代码。

推荐答案

@the4kman，@krunal，感谢您的回复！解决方案就更简单了。将let formattedString = "u{2022} (string) 中的空格符号替换为 可提供有效的缩进。

为完整起见，完整的解决方案代码为(只需替换一个字符)：

func add(bulletList strings: [String],
         font: UIFont,
         indentation: CGFloat = 15,
         lineSpacing: CGFloat = 3,
         paragraphSpacing: CGFloat = 10,
         textColor: UIColor = .black,
         bulletColor: UIColor = .red) -> NSAttributedString {

    func createParagraphAttirbute() -> NSParagraphStyle {
        var paragraphStyle: NSMutableParagraphStyle
        let nonOptions = NSDictionary() as! [NSTextTab.OptionKey: Any]

        paragraphStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
        paragraphStyle.tabStops = [
            NSTextTab(textAlignment: .left, location: indentation, options: nonOptions)]
        paragraphStyle.defaultTabInterval = indentation
        paragraphStyle.firstLineHeadIndent = 0
        paragraphStyle.lineSpacing = lineSpacing
        paragraphStyle.paragraphSpacing = paragraphSpacing
        paragraphStyle.headIndent = indentation
        return paragraphStyle
    }

    let bulletPoint = "u{2022}"
    let textAttributes: [NSAttributedStringKey: Any] = [.font: font, .foregroundColor: textColor]
    let bulletAttributes: [NSAttributedStringKey: Any] = [.font: font, .foregroundColor: bulletColor]
    let buffer = NSMutableAttributedString.init()

    for string in strings {
        let formattedString = "(bulletPoint)	(string)
"
        let attributedString = NSMutableAttributedString(string: formattedString)
        let paragraphStyle = createParagraphAttirbute()

        attributedString.addAttributes(
            [NSAttributedStringKey.paragraphStyle : paragraphStyle],
            range: NSMakeRange(0, attributedString.length))

        attributedString.addAttributes(
            textAttributes,
            range: NSMakeRange(0, attributedString.length))

        let string:NSString = NSString(string: formattedString)
        let rangeForBullet:NSRange = string.range(of: bulletPoint)
        attributedString.addAttributes(bulletAttributes, range: rangeForBullet)
        buffer.append(attributedString)
    }

    return buffer
}

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