attr_string

attr_string is a C++ wrapper around NSAttributedString designed to make constructing attributed strings easier (and less verbose).

Usage

To start using attr_string, just copy attr_string.h into your project and #import it. You may want to add using namespace attr_string; on a line after the #import to reduce typing (all the examples here and in the demo assume this).

attr_string lets you build up an attributed string by adding attributes and content. Attributes you add will apply to all the content after them (until they are removed).

For example, you can easily create a bold label followed by normal text:

attr_string_t msg;
msg.add(style::bold);
msg.add("Label: ");
msg.add(style::unbold);
msg.add("Normal Text");

Or inline:

[field setAttributedStringValue:(attr_string_t(style::bold) << "Label: " << style::unbold << "Normal Text")];

An equivalent using NSAttributedString:

NSFont* boldFont                   = [NSFont boldSystemFontOfSize:12];
NSDictionary* boldFontAttributes   = [NSDictionary dictionaryWithObject:boldFont forKey:NSFontAttributeName];
NSMutableAttributedString* attrMsg = [[[NSMutableAttributedString alloc] initWithString:@"Label: " attributes:boldFontAttributes] autorelease];
[attrMsg appendAttributedString:[[[NSMutableAttributedString alloc] initWithString:@"Normal Text " attributes:nil] autorelease]];

You can use an attr_string_t wherever you’d pass an NSAttributedString, though you may need to explicitly cast it in some cases (notably when calling an NSAttributedString method, for example [(NSAttributedString*)msg drawInRect:rect]).

Styles

See the style::type enum for available styles, currently there are styles for bold, underline, italic and embossed text. As well as the style::type constants, you can also pass an NSFont, NSColor (use style::background([NSColor redColor]) to set a background colour), NSShadow, and even an NSImage, and they’ll do the right thing. Passing an NSString or a char* will append the text with the currently set styles.

Caveats

Literal NSStrings (e.g. @"Foo bar") are actually not typed as instances of NSString at compile-time, which means that you cannot pass them directly to attr_string_t without casting as (NSString*). You can use a C-string literal instead though, and any methods which return an NSString* will be usable without casting.

Unfortunately +[NSImage imageNamed:] returns an id rather than an NSImage*, which means that it must be casted to be passed directly to attr_string_t.