Convert NSAttributedString to string and back

Question

I have NSString and I need to make NSAttributedString.

NSString is something like:

bvcx b vcxbcvx bcxvbcxv bvx xbc bcvx bxcv bcxv bcxv bcxv bcvx bcvx bcxvbcvx bvc bcvx bxcv{
NSFont = "\"LucidaGrande 24.00 pt. P [] (0x108768a80) fobj=0x108788880, spc=7.59\"";
NSParagraphStyle = "Alignment 4, LineSpacing 0, ParagraphSpacing 0, ParagraphSpacingBefore 0, HeadIndent 0, TailIndent 0, FirstLineHeadIndent 0, LineHeight 0/0, LineHeightMultiple 0, LineBreakMode 0, Tabs (\n    28L,\n    56L,\n    84L,\n    112L,\n    140L,\n    168L,\n    196L,\n    224L,\n    252L,\n    280L,\n    308L,\n    336L\n), DefaultTabInterval 0, Blocks (null), Lists (null), BaseWritingDirection -1, HyphenationFactor 0, TighteningFactor 0.05, HeaderLevel 0";
}

It's NSAttributedString in UTF-8. Is there any way how to do that?

Answer 1

You said you created your input string from an existing NSAttributedString like this:

[NSString stringWithFormat:@"%@", nsattributedstring]

The %@ format specifier sends the description message to the nsattributedstring object. The description method is not designed to produce a string that can be easily converted back to an NSAttributedString object. It is designed to help programmers debug their code.

The process of converting an object to a string, or an array of bytes, so that it can be converted back to an object later, is called serialization. Using %@ or the description method is generally not a good way to perform serialization. If you really want to deserialize the string created by the description method, you'll have to write your own parser. As far as I know, there is no API for that.

Instead, Cocoa provides a system designed to serialize and deserialize objects. Objects that can be serialized using this system conform to the NSCoding protocol. NSAttributedString objects conform to NSCoding. So try serializing your original attributed string this way:

NSMutableData *data = [NSKeyedArchiver archivedDataWithRootObject:nsattributedstring];

Save data (which is non-human-readable binary, not UTF-8) wherever you need to. When you need to recreate the attributed string, do this:

NSAttributedString *fancyText = [NSKeyedUnarchiver unarchiveObjectWithData:data];

If you are programming for OS X (not iOS), you have an alternative. You can turn an attributed string into RTF (rich text format), which is fairly human-readable, using the RTFFromRange:documentAttributes: method (which omits attachments) or the RTFDFromRange:documentAttributes: method (which includes attachments). Then you can turn the RTF data back into an attributed string using initWithRTF:documentAttributes: or initWithRTFD:documentAttributes:. These methods are not available on iOS.

If you are programming for iOS 7.0 or later, you can use -dataFromRange:documentAttributes:error: or fileWrapperFromRange:documentAttributes:error: to convert the attributed string to RTF/RTFD. You need to set NSDocumentTypeDocumentAttribute to NSRTFTextDocumentType or NSRTFDTextDocumentType in the document attributes. Use initWithData:options:documentAttributes:error: or initWithFileURL:options:documentAttributes:error: to convert back to an NSAttributedString. These methods are part of the NSAttributedString UIKit Additions.