NSMutableAttributedString add different alignments

Question

Is it possible to add left and right alignments to different parts of the string?

I tried to add alignment attribute to the right part:

    NSMutable         


        

Answer 1

Building on @Verglas's answer...

The way you'd normally do something like this in HTML is via floating. Something like this::

Left
Right

It would be great if you could transform this into a NSAttributedString and have it work:

NSString* html = @"
Left
Right
";

NSData* d = [html dataUsingEncoding: NSUTF8StringEncoding];

NSAttributedString* as = [[NSMutableAttributedString alloc] initWithData: d
                                               options: @{
                                                          NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,
                                                          NSCharacterEncodingDocumentAttribute : @(NSUTF8StringEncoding)
                                                          }
                                    documentAttributes: nil
                                                 error: nil];

Sadly, it does not work.

For a second attempt, we can try using a HTML table:

html = @"
Left
Right
";

Curiously, this works as intended. What's even more curious are the attributes it generates:

2014-08-27 14:27:31.443 testParagraphStyles[2095:60b] range: {0, 5} attributes: {
     NSParagraphStyle = "Alignment 4, LineSpacing 0, ParagraphSpacing 0, ParagraphSpacingBefore 0, HeadIndent 0, TailIndent 0, FirstLineHeadIndent 0, LineHeight 0/0, LineHeightMultiple 0, LineBreakMode 0, Tabs (\n), DefaultTabInterval 36, Blocks (\n    \"\"\n), Lists (null), BaseWritingDirection 0, HyphenationFactor 0, TighteningFactor 0, HeaderLevel 0";

2014-08-27 14:27:31.444 testParagraphStyles[2095:60b] range: {5, 6} attributes: {
    NSParagraphStyle = "Alignment 2, LineSpacing 0, ParagraphSpacing 0, ParagraphSpacingBefore 0, HeadIndent 0, TailIndent 0, FirstLineHeadIndent 0, LineHeight 0/0, LineHeightMultiple 0, LineBreakMode 0, Tabs (\n), DefaultTabInterval 36, Blocks (\n    \"\"\n), Lists (null), BaseWritingDirection 0, HyphenationFactor 0, TighteningFactor 0, HeaderLevel 0";
}

Scroll to the right and notice the reference to NSTextTableBlock. NSTextTable isn't a public API on iOS, but NSAttributedString initWithData:options:documentAttributes:error: used it to generate our attributed string from HTML. This is painful because it means we can't construct a NSAttributedString by hand (we must generate it fro HTML using this API).

Building attributed strings from HTML is slow and largely undocumented. I avoid it whenever I can.