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一尘不染

将属性字符串转换为“简单”标记的html

swift

我想将NSAttributedString转换为html，如下所示：

This is a <i>string</i> with some <b>simple</b> <i><b>html</b></i> tags in it.

不幸的是，如果您使用Apple的内置系统，它将生成基于CSS的详细html。（以下示例仅供参考。）

那么如何从NSAttributedString生成简单的带标签的html？

我写了一个非常冗长，脆弱的电话来做，这是一个糟糕的解决方案。

func simpleTagStyle(fromNSAttributedString att: NSAttributedString)->String {

    // verbose, fragile solution

    // essentially, iterate all the attribute ranges in the attString
    // make a note of what style they are, bold italic etc
    // (totally ignore any not of interest to us)
    // then basically get the plain string, and munge it for those ranges.
    // be careful with the annoying "multiple attribute" case
    // (an alternative would be to repeatedly munge out attributed ranges
    // one by one until there are none left.)

    let rangeAll = NSRange(location: 0, length: att.length)

    // make a note of all of the ranges of bold/italic
    // (use a tuple to remember which is which)
    var allBlocks: [(NSRange, String)] = []

    att.enumerateAttribute(
        NSFontAttributeName,
        in: rangeAll,
        options: .longestEffectiveRangeNotRequired
        )
            { value, range, stop in

            handler: if let font = value as? UIFont {

                let b = font.fontDescriptor.symbolicTraits.contains(.traitBold)
                let i = font.fontDescriptor.symbolicTraits.contains(.traitItalic)

                if b && i {
                    allBlocks.append( (range, "bolditalic") )
                    break handler   // take care not to duplicate
                }

                if b {
                    allBlocks.append( (range, "bold") )
                    break handler
                }

                if i {
                    allBlocks.append( (range, "italic") )
                    break handler
                }
            }

        }

    // traverse those backwards and munge away

    var plainString = att.string

    for oneBlock in allBlocks.reversed() {

        let r = oneBlock.0.range(for: plainString)!

        let w = plainString.substring(with: r)

        if oneBlock.1 == "bolditalic" {
            plainString.replaceSubrange(r, with: "<b><i>" + w + "</i></b>")
        }

        if oneBlock.1 == "bold" {
            plainString.replaceSubrange(r, with: "<b>" + w + "</b>")
        }

        if oneBlock.1 == "italic" {
            plainString.replaceSubrange(r, with: "<i>" + w + "</i>")
        }

    }

    return plainString
}

因此，这是使用Apple内置系统的方法，该系统不幸地生成了完整的CSS等。

x = ... your NSAttributedText
var resultHtmlText = ""
do {

    let r = NSRange(location: 0, length: x.length)
    let att = [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType]

    let d = try x.data(from: r, documentAttributes: att)

    if let h = String(data: d, encoding: .utf8) {
        resultHtmlText = h
    }
}
catch {
    print("utterly failed to convert to html!!! \n>\(x)<\n")
}
print(resultHtmlText)

输出示例…

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta http-equiv="Content-Style-Type" content="text/css">
<title></title>
<meta name="Generator" content="Cocoa HTML Writer">
<style type="text/css">
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px 'Some Font'}
span.s1 {font-family: 'SomeFont-ItalicOrWhatever'; font-weight: normal; font-style: normal; font-size: 14.00pt}
span.s2 {font-family: 'SomeFont-SemiboldItalic'; font-weight: bold; font-style: italic; font-size: 14.00pt}
</style>
</head>
<body>
<p class="p1"><span class="s1">So, </span><span class="s2">here is</span><span class="s1"> some</span> stuff</p>
</body>
</html>

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2020-07-07

共1个答案

一尘不染

根据的文档enumerateAttribute:inRange:options:usingBlock:，特别是“
讨论” 部分，其中指出：

如果将此方法发送到NSMutableAttributedString的实例，则允许其突变（删除，添加或更改），只要它在提供给该块的范围内即可；突变后，在针对突变调整了加工范围的长度之后，枚举将继续紧接在加工范围之后的范围。（枚举器基本上假定长度的任何变化都发生在指定范围内。）例如，如果调用的块的范围从位置N开始，并且该块删除了所提供范围内的所有字符，则下一次调用也将传递N作为范围的索引。

换句话说，在闭包/块中，使用range，您可以在那里删除/替换字符。操作系统将在范围的末端放置一个标记。进行修改后，它将计算标记的新范围，以便下一次枚举迭代将从该新标记开始。因此，您不必将所有范围都保留在一个数组中，而是通过向后替换而不修改范围来应用更改。不用为此烦恼，方法已经做到了。

我不是Swift开发人员，而是Objective-C开发人员。因此我的Swift代码可能不遵守所有的“
Swift规则”，并且可能有点丑陋（可选，包装等处理不当，if let未完成等）。

这是我的解决方案：

func attrStrSimpleTag() -> Void {

    let htmlStr = "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01//EN\" \"http://www.w3.org/TR/html4/strict.dtd\"> <html> <head> <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"> <meta http-equiv=\"Content-Style-Type\" content=\"text/css\"> <title></title> <meta name=\"Generator\" content=\"Cocoa HTML Writer\"> <style type=\"text/css\"> p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px 'Some Font'} span.s1 {font-family: 'SomeFont-ItalicOrWhatever'; font-weight: normal; font-style: normal; font-size: 14.00pt} span.s2 {font-family: 'SomeFont-SemiboldItalic'; font-weight: bold; font-style: italic; font-size: 14.00pt} </style> </head> <body> <p class=\"p1\"><span class=\"s1\">So, </span><span class=\"s2\">here is</span><span class=\"s1\"> some</span> stuff</p> </body></html>"
    let attr = try! NSMutableAttributedString.init(data: htmlStr.data(using: .utf8)!,
                                                   options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType],
                                                   documentAttributes: nil)
    print("Attr: \(attr)")
    attr.enumerateAttribute(NSFontAttributeName, in: NSRange.init(location: 0, length: attr.length), options: []) { (value, range, stop) in
        if let font = value as? UIFont {
            print("font found:\(font)")
            let isBold = font.fontDescriptor.symbolicTraits.contains(.traitBold)
            let isItalic = font.fontDescriptor.symbolicTraits.contains(.traitItalic)
            let occurence = attr.attributedSubstring(from: range).string
            let replacement = self.formattedString(initialString: occurence, bold: isBold, italic: isItalic)
            attr.replaceCharacters(in: range, with: replacement)
        }
    };

    let taggedString = attr.string
    print("taggedString: \(taggedString)")

}

func formattedString(initialString:String, bold: Bool, italic: Bool) -> String {
    var retString = initialString
    if bold {
        retString = "<b>".appending(retString)
        retString.append("</b>")
    }
    if italic
    {
        retString = "<i>".appending(retString)
        retString.append("</i>")
    }

    return retString
}

输出（对于最后一个，其他两个打印仅用于调试）：

$> taggedString: So, <i><b>here is</b></i> some stuff

编辑： Objective-C版本（快速编写，可能有问题）。

-(void)attrStrSimpleTag
{
    NSString *htmlStr = @"<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01//EN\" \"http://www.w3.org/TR/html4/strict.dtd\"> <html> <head> <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"> <meta http-equiv=\"Content-Style-Type\" content=\"text/css\"> <title></title> <meta name=\"Generator\" content=\"Cocoa HTML Writer\"> <style type=\"text/css\"> p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px 'Some Font'} span.s1 {font-family: 'SomeFont-ItalicOrWhatever'; font-weight: normal; font-style: normal; font-size: 14.00pt} span.s2 {font-family: 'SomeFont-SemiboldItalic'; font-weight: bold; font-style: italic; font-size: 14.00pt} </style> </head> <body> <p class=\"p1\"><span class=\"s1\">So, </span><span class=\"s2\">here is</span><span class=\"s1\"> some</span> stuff</p> </body></html>";
    NSMutableAttributedString *attr = [[NSMutableAttributedString alloc] initWithData:[htmlStr dataUsingEncoding:NSUTF8StringEncoding]
                                                                              options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType}
                                                                   documentAttributes:nil
                                                                                error:nil];
    NSLog(@"Attr: %@", attr);

    [attr enumerateAttribute:NSFontAttributeName inRange:NSMakeRange(0, [attr length]) options:0 usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop) {
        UIFont *font = (UIFont *)value;
        NSLog(@"Font found: %@", font);
        BOOL isBold =  UIFontDescriptorTraitBold & [[font fontDescriptor] symbolicTraits];
        BOOL isItalic =  UIFontDescriptorTraitItalic & [[font fontDescriptor] symbolicTraits];
        NSString *occurence = [[attr attributedSubstringFromRange:range] string];
        NSString *replacement = [self formattedStringWithString:occurence isBold:isBold andItalic:isItalic];
        [attr replaceCharactersInRange:range withString:replacement];
    }];

    NSString *taggedString = [attr string];
    NSLog(@"taggedString: %@", taggedString);
}


-(NSString *)formattedStringWithString:(NSString *)string isBold:(BOOL)isBold andItalic:(BOOL)isItalic
{
    NSString *retString = string;
    if (isBold)
    {
        retString = [NSString stringWithFormat:@"<b>%@</b>", retString];
    }
    if (isItalic)
    {
        retString = [NSString stringWithFormat:@"<i>%@</i>", retString];
    }
    return retString;
}

2020年1月编辑：
更新了代码，具有更轻松的修改和Swift 5，增加了对两个新效果（下划线/删除线）的支持。

// MARK: In one loop
extension NSMutableAttributedString {
    func htmlSimpleTagString() -> String {
        enumerateAttributes(in: fullRange(), options: []) { (attributes, range, pointeeStop) in
            let occurence = self.attributedSubstring(from: range).string
            var replacement: String = occurence
            if let font = attributes[.font] as? UIFont {
                replacement = self.font(initialString: replacement, fromFont: font)
            }
            if let underline = attributes[.underlineStyle] as? Int {
                replacement = self.underline(text: replacement, fromStyle: underline)
            }
            if let striked = attributes[.strikethroughStyle] as? Int {
                replacement = self.strikethrough(text: replacement, fromStyle: striked)
            }
            self.replaceCharacters(in: range, with: replacement)
        }
        return self.string
    }
}

// MARK: In multiple loop
extension NSMutableAttributedString {
    func htmlSimpleTagString(options: [NSAttributedString.Key]) -> String {
        if options.contains(.underlineStyle) {
            enumerateAttribute(.underlineStyle, in: fullRange(), options: []) { (value, range, pointeeStop) in
                let occurence = self.attributedSubstring(from: range).string
                guard let style = value as? Int else { return }
                if NSUnderlineStyle(rawValue: style) == NSUnderlineStyle.styleSingle {
                    let replacement = self.underline(text: occurence, fromStyle: style)
                    self.replaceCharacters(in: range, with: replacement)
                }
            }
        }
        if options.contains(.strikethroughStyle) {
            enumerateAttribute(.strikethroughStyle, in: fullRange(), options: []) { (value, range, pointeeStop) in
                let occurence = self.attributedSubstring(from: range).string
                guard let style = value as? Int else { return }
                let replacement = self.strikethrough(text: occurence, fromStyle: style)
                self.replaceCharacters(in: range, with: replacement)
            }
        }
        if options.contains(.font) {
            enumerateAttribute(.font, in: fullRange(), options: []) { (value, range, pointeeStop) in
                let occurence = self.attributedSubstring(from: range).string
                guard let font = value as? UIFont else { return }
                let replacement = self.font(initialString: occurence, fromFont: font)
                self.replaceCharacters(in: range, with: replacement)
            }
        }
        return self.string

    }
}

//MARK: Replacing
extension NSMutableAttributedString {

    func font(initialString: String, fromFont font: UIFont) -> String {
        let isBold = font.fontDescriptor.symbolicTraits.contains(.traitBold)
        let isItalic = font.fontDescriptor.symbolicTraits.contains(.traitItalic)
        var retString = initialString
        if isBold {
            retString = "<b>" + retString + "</b>"
        }
        if isItalic {
            retString = "<i>" + retString + "</i>"
        }
        return retString
    }

    func underline(text: String, fromStyle style: Int) -> String {
        return "<u>" + text + "</u>"
    }

    func strikethrough(text: String, fromStyle style: Int) -> String {
        return "<s>" + text + "</s>"
    }
}

//MARK: Utility
extension NSAttributedString {
    func fullRange() -> NSRange {
        return NSRange(location: 0, length: self.length)
    }
}

简单的HTML以测试混合标签： "This is <i>ITALIC</i> with some <b>BOLD</b> <b><i>BOLDandITALIC</b></i> <b>BOLD<u>UNDERLINEandBOLD</b>RESTUNDERLINE</u> in it."

解决方案带来了两种方法：一种执行一个循环，另一种执行多个循环，但是对于混合标签，结果可能很奇怪。与之前提供的样本检查不同的渲染。

2020-07-07