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UILabel that supports NSAttributedString

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About these classes

OHAttributedLabel

This class allows you to use a UILabel with NSAttributedStrings, in order to display styled text with various style (mixed fonts, color, size, ...) in a unique label. It is a subclass of UILabel which adds an attributedText property. Use this property, instead of the text property, to set and get the NSAttributedString to display.

Note: This class is compatible with iOS4.3+ and has been developped before the release of the iOS6 SDK (before Apple added support for NSAttributedLabel in the UILabel class itself). It can still be used with the iOS6 SDK (the attributedText property hopefully match the one chosen by Apple) if you need support for eariler iOS versions or for the additional features it provides.

This class also support hyperlinks and URLs. It can automatically detect links in your text, color them and make them touchable; you can also add "custom links" in your text by attaching an URL to a range of your text and thus make it touchable, and even then catch the event of a touch on a link to act as you wish to.

NSAttributedString and NSTextChecking additions

In addition to this OHAttributedLabel class, you will also find a category of NS(Mutable)AttributedString to ease creation and manipulation of common attributes of NSAttributedString (to easily change the font, style, color, ... of a range of the string). See the header file NSAttributedString+Attributes.h for a list of those comodity methods.

Example:

// Build an NSAttributedString easily from a NSString
NSMutableAttributedString* attrStr = [NSMutableAttributedString attributedStringWithString:txt];
// Change font, text color, paragraph style
[attrStr setFont:[UIFont fontWithName:@"Helvetica" size:18]];
[attrStr setTextColor:[UIColor grayColor]];

OHParagraphStyle* paragraphStyle = [OHParagraphStyle defaultParagraphStyle];
paragraphStyle.textAlignment = kCTJustifiedTextAlignment;
paragraphStyle.lineBreakMode = kCTLineBreakByWordWrapping;
paragraphStyle.firstLineHeadIndent = 30.f; // indentation for first line
paragraphStyle.lineSpacing = 3.f; // increase space between lines by 3 points
[attrStr setParagraphStyle:paragraphStyle];

// Change the color and bold of only one part of the string
[attrStr setTextColor:[UIColor redColor] range:NSMakeRange(10,3)];
[attrStr setTextBold:YES range:NSMakeRange(10,8)];

// Add a link to a given portion of the string
[attrStr setLink:someNSURL range:NSMakeRange(8,20)];

There is also a category for NSTextCheckingResult that adds the extendedURL property. This property returns the same value as the URL value for standard link cases, and return a formatted Maps URL for NSTextCheckingTypeAddress link types, that will open Google Maps in iOS version before 6.0 and the Apple's Maps application in iOS 6.0 and later.

OHASMarkupParsers and simple markup to build your attributed strings easily

The library also comes with very simple tag parsers to help you build NSAttributedStrings easily using very simple tags.

  • the class OHASBasicHTMLParser can parse simple HTML tags like <b> and <u> to make bold and underlined text, change the font color using <font color='…'>, etc
  • the class OHASBasicMarkupParser can parse simple markup like *bold text*, _underlined text_ and change the font color using markup like {red|some red text} or {#ff6600|Yeah}.

    // Example 1: parse HTML in attributed string
    basicMarkupLabel.attributedText = [OHASBasicHTMLParser attributedStringByProcessingMarkupInAttributedString:basicMarkupLabel.attributedText];
    
    // Example 2: parse basic markup in string
    NSAttributedString* as = [OHASBasicMarkupParser attributedStringByProcessingMarkupInString:@"Hello *you*!"];
    
    // Example 3: //process markup in-place in a mutable attributed string
    NSMutableAttributedString* mas = [NSMutableAttributedString attributedStringWithString:@"Hello *you*!"];
    [OHASBasicMarkupParser processMarkupInAttributedString:mas];
    

Note that OHASBasicHTMLParser is intended to be a very simple tool only to help you build attributed string easier: this is not intended to be a real and complete HTML interpreter, and will never be. For improvements of this feature, like adding other tags or markup languages, refer to issue #88)

UIAppearance support

The OHAttributedLabel class support the UIAppearance proxy API (available since iOS5). See selectors and properties marked using the UI_APPEARANCE_SELECTOR in the header.

This means that if you are targetting iOS5, you can customize all of your OHAttributedLabel links color and underline style to fit your application design, only in one call at the beginning of your application, instead of having to customize these for each instance.

For example, your could implement this in your application:didFinishLoadingWithOptions: delegate method to make all your OHAttributedLabel instances in your whole app display links in green and without underline instead of the default underlined blue:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [ [OHAttributedLabel appearance] setLinkColor:[UIColor colorWithRed:0.0 green:0.4 blue:0.0 alpha:1.0] ];
    [ [OHAttributedLabel appearance] setLinkUnderlineStyle:kCTUnderlineStyleNone ];
    return YES;
}

How to use in your project

There are three possible methods to include these classes in your project:

  1. Using Cocoapods:

    • add pod "OHAttributedLabel" to your Podfile
  2. Include OHAttributedLabel in your project:

    • Include the OHAttributedLabel.xcodeproj project in your Xcode4 workspace
    • Build this OHAttributedLabel.xcodeproj project once for the "iOS Device" (not the simulator) (1)
    • Add libOHAttributedLabel.a and CoreText.framework to your "Link Binary With Libraries" Build Phase of your app project.
    • Select the libOHAttributedLabel.a that has just been added to your app project in your Project Navigator on the left, and change the "Location" dropdown in the File Inspector to "Relative to Build Products" (1)
    • Add the -ObjC flag in the "Other Linker Flags" Build Setting (if not present already)
  3. Add libOHAttributedLabel.a and headers in your project

    • cd OHAttributedLabel
    • make clean && make (nb. rvm users may need to CC= && make clean && make)
    • copy the contents of the build/Release-Combined directory to you project (eg. ThirdParty/OHAttributedLabel)
    • Add libOHAttributedLabel.a and CoreText.framework to your "Link Binary With Libraries" Build Phase of your app project.
    • Add the OHAttributedLabel headers to your "Header Search Path" in Build Settings (eg. "$(SRCROOT)/ThirdParty/OHAttributedLabel/include/**")
    • Add the -ObjC flag in the "Other Linker Flags" Build Setting (if not present already)

Then in your application code, when you want to make use of OHAttributedLabel methods, you only need to import the headers with #import <OHAttributedLabel/OHAttributedLabel.h> or #import <OHAttributedLabel/NSAttributedString+Attributes.h> etc.

(1) Note: These two steps are only necessary to avoid a bug in Xcode4 that would otherwise make Xcode fail to detect implicit dependencies between your app and the lib.

For more details and import/linking troubleshooting, please see the dedicated page.

Sample code & Other documentation

There is no explicit docset or documentation of the class yet sorry (never had time to write one), but

  • The method names should be self-explanatory (hopefully) as I respect the standard ObjC naming conventions.
  • There are doxygen/javadoc-like documentation in the headers that should also help you describe the methods
  • The provided example ("AttributedLabel Example.xcworkspace") should also demonstrate quite every typical usages — including justifying the text, dynamically changing the style/attributes of a range of text, adding custom links, make special links with a custom behavior (like catching @mention and #hashtags), and customizing the appearance/color of links.

License & Credits

OHAttributedLabel is published under the MIT license. It has been created and developped by me (O.Halligon), but I'd like to thank all the contributors too, including @mattjgalloway, @stigi and @jparise among others.

ChangeLog — Revisions History

The ChangeLog is maintained as a wiki page accessible here.

Projects that use this class

Here is a non-exhaustive list of the projects that use this class (for those who told me about it) Feel free to contact me if you use this class so we can cross-reference our projects and quote your app in this dedicated wiki page!

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