Convert attributed string to "plain" tagged html
I want to convert NSAttributedString to html like this:
This is a <i>string</i> with some <b>simple</b> <i><b>html</b></i> tags in it.
Unfortunately, if you are using Apple's built-in system, it generates verbose CSS-html. (The example below is for reference.)
So how do I create simple tagged html from NSAttributedString?
I wrote a very verbose, fragile call to do this, which is a bad decision.
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
}
So how do you use Apple's built-in system, which unfortunately generates fully functional CSS, etc.
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)
Sample output ....
<!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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According to the documentation enumerateAttribute:inRange:options:usingBlock:
, especially the part of the discussion that says:
If this method is sent to an NSMutableAttributedString instance, mutation (deletion, addition, or modification) is allowed if it is within the range provided for the block; after mutation, the enumeration continues with the range following the range to be processed, after the length of the range to be processed for the mutation has been adjusted. (The enumerator basically assumes any change in length occurs in the specified range.) For example, if a block is called with a range starting at position N and the block removes all characters in the supplied range, the next call will also pass N as the range index.
In other words, in the lock / block with, range
you can remove / replace characters there. The OS will place a marker at this end of the range. After you've made your changes, it will compute a new marker range so that the next iteration of the enumeration will start at that new marker. This way, you don't have to keep all ranges in the array and apply the changes afterwards, doing the reverse replacement so as not to change the range. Don't worry about it, the methods are already doing it.
I'm not a fast developer, I'm more Objective-C. So my Swift code might not respect all "Swift rules" and might be a little ugly (optional, wrapping, etc. Badly done, if let
not done, etc.)
Here is my solution:
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
}
Output (for the latter, the other two fingerprints are for debugging only):
$> taggedString: So, <i><b>here is</b></i> some stuff
Edit: Objective-C Version (quick written, maybe some problem).
-(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;
}
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I have a nice way to convert NSAttributedString to plain HTML string .
1) Take UIWebView and UITextView .
2) Set the Attributed line to the WebView .
[webView loadHTMLString:[yourAttributedString stringByReplacingOccurrencesOfString:@"\n" withString:@"<br/>"] baseURL:nil];
3) Get HTML string from UIWebView .
NSString *simpleHtmlString = [webView stringByEvaluatingJavaScriptFromString:@"document.body.innerHTML"];
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