Convert attributed string, to, “simple” tagged html

Question

I want to convert an NSAttributedString, to html like this:

This is a string with some simple html<         


        

Answer 1

Here's a more complete solution that preserves more styles and links.

Check out the other keys in NSAttributedString.h if you want to preserve color and kerning information.

@implementation NSAttributedString (SimpleHTML)

- (NSString*) simpleHTML
{
    NSMutableAttributedString*  attr = [self mutableCopy];

    [attr enumerateAttributesInRange: NSMakeRange(0, [self length])
                             options: 0
                          usingBlock: ^(NSDictionary * _Nonnull attrs, NSRange range, BOOL * _Nonnull stop)
    {
        for (NSString* aKey in attrs.allKeys.copy)
        {
            NSString*   format          =   nil;

            if ([aKey compare: NSFontAttributeName] == NSOrderedSame) //UIFont, default Helvetica(Neue) 12
            {
                UIFont* font = attrs[aKey];

                BOOL isBold =  UIFontDescriptorTraitBold & [[font fontDescriptor] symbolicTraits];
                BOOL isItalic =  UIFontDescriptorTraitItalic & [[font fontDescriptor] symbolicTraits];

                if (isBold && isItalic)
                {
                    format = @"%@";
                }
                else if (isBold)
                {
                    format = @"%@";
                }
                else if (isItalic)
                {
                    format = @"%@";
                }
            }
            else if ([aKey compare: NSStrikethroughStyleAttributeName] == NSOrderedSame) //NSNumber containing integer, default 0: no strikethrough
            {
                NSNumber*   strike  =   (id) attrs[aKey];

                if (strike.boolValue)
                {
                    format = @"";
                }
                else
                {
                    format = @"";
                }
            }
            else if ([aKey compare: NSUnderlineStyleAttributeName] == NSOrderedSame) //NSNumber containing integer, default 0: no underline
            {
            if ([attrs.allKeys containsObject: NSLinkAttributeName] == NO)
                {
                    NSNumber*   underline  =   (id) attrs[aKey];

                    if (underline.boolValue)
                    {
                        format = @"%@";
                    }
                }
            }
            else if ([aKey compare: NSLinkAttributeName] == NSOrderedSame) //NSURL (preferred) or NSString
            {
                NSObject*   value       =   (id) attrs[aKey];
                NSString*   absolute    =   @"";

                if ([value isKindOfClass: NSURL.class])
                {
                    NSURL*      url =   (id) value;

                    absolute = url.absoluteString;
                }
                else if ([value isKindOfClass: NSString.class])
                {
                    absolute = (id) value;
                }

                format = [NSString stringWithFormat: @"%%@", absolute];
            }

            if (format)
            {
                NSString*   occurence   =   [[attr attributedSubstringFromRange: range] string];
                NSString*   replacement =   [NSString stringWithFormat: format, occurence];

                [attr replaceCharactersInRange: range
                                    withString: replacement];
            }
        }
    }];

    NSMutableString*    result  =   [[NSString stringWithFormat: @"%@", attr.string] mutableCopy];

    [result replaceOccurrencesOfString: @"\n"
                            withString: @"
"
                               options: 0
                                 range: NSMakeRange(0, result.length)];

    return result;
}

@end

EDIT: I've added the conditional you need to check to enable/disable underline detection while it's treating a URL.