A block-based API for NSValueTransformer, with a growing collection of useful examples.

NSValueTransformer, while perhaps obscure to most iOS programmers, remains a staple of OS X development. Before Objective-C APIs got in the habit of flinging block parameters hither and thither with reckless abandon, NSValueTransformer was the go-to way to encapsulate mutation functionality --- especially when it came to Bindings.

NSValueTransformer is convenient to use but a pain to set up. To create a value transformer you have to create a subclass, implement a handful of required methods, and register a singleton instance by name.

TransformerKit breathes new life into NSValueTransformer by making them dead-simple to define and register:

NSString * const TTTCapitalizedStringTransformerName = @"TTTCapitalizedStringTransformerName";
[NSValueTransformer registerValueTransformerWithName:TTTCapitalizedStringTransformerName
                               transformedValueClass:[NSString class]
                  returningTransformedValueWithBlock:^id(id value) {
  return [value capitalizedString];
}];

TransformerKit pairs nicely with InflectorKit and FormatterKit, providing well-designed APIs for manipulating user-facing content.

TransformerKit also contains a growing number of convenient transformers that your apps will love and cherish:

• Capitalized
• UPPERCASE
• lowercase
• CamelCase
• llamaCase
• snake_case
• train-case
• esreveR* (Reverse)
• Rémövê Dîaçritics (Remove accents and combining marks)
• ट्रांस्लितेराते स्ट्रिंग (Transliterate to Latin)
• Any Valid ICU Transform*

• PNG Representation*
• JPEG Representation*
• GIF Representation (macOS)
• TIFF Representation (macOS)

• ISO 8601 Timestamp*
• RFC 2822 Timestamp*

• JSON Transformer*

• Base16 String Encode / Decode
• Base32 String Encode / Decode
• Base64 String Encode / Decode
• Base85 String Encode / Decode

• MD5, SHA-1, SHA-256, et al. Digests

* - Reversible

Mattt (@mattt)

TransformerKit is released under the MIT license. See the LICENSE file for more info.