Unlike other Java to Objective-C solutions, Java-Objective-C Bridge doesn't require any code generation of class stubs. It allows you to use any Objective-C libraries and frameworks from Java without having to write any native code. In addition to being able to use Objective-C objects, it allows you to pass Java objects to the objective-c runtime as delegates, so that you can write an entire Cocoa application in Java. The bridge provides 3 levels of abstraction. At the lowest level, it provides wrappers around the Objective-C runtime functions. At a slightly higher level of abstraction, it provides a procedural API to send messages to the Objective-C runtime. At the highest level of abstraction, it provides a Proxy class that serves as a wrapper around any Objective-C object that allows you to work with it in Java almost the same as if you were in Objective-C.
OFXKit is an Objective-C framework for parsing OFX files into a class hierarchy. Since OFXKit is a native Cocoa framework, Mac OS X development technologies can be easily used with OFXKit. Its main features include OFX 1.x and 2.x support, banking, loan, and investment message sets, and creation of OFX request documents for the "Direct-Connect" feature of many banking Web sites.
J2ObjC is a tool from Google that translates Java code to Objective-C for the iOS platform. It enables Java code to be part of an iOS build, as no editing of the generated files is necessary. The goal is to write an app's non-UI code (such as data access or application logic) in Java, which can then be shared by Web apps using GWT, Android apps, and iOS apps. J2ObjC supports most Java language and runtime features required by client-side application developers, including exceptions, inner and anonymous classes, generic types, threads, and reflection. JUnit test translation and execution are also supported.
LibRCrypt is an Objective C library for complex data encryption based on Rubik's Cubes. The idea's pretty simple: If you represent data as the squares on a Rubik's Cube, you can apply transformations to the data and get back encrypted data, all of which is commutatitive. Just as a Rubik's Cube can be solved if you know all of the moves, this data can be "unwound", so to speak, if you know all of the transforms applied, but the encryption is even deeper than that. A cube can only cover (9 squares per face x 6 faces) 54 significant bits of data. Therefore, compressed data must be composed of multiple (even thousands) of Rubik's Cubes.
DSFoundation is a foundation enhancement library for Objective-C. It includes an IOC (Inversion of Control) container, translation (serialization and conversion) to and from Objects, YAML, and XML, automatic KVC adaptation and compliance, logging through an integrated Log4Cocoa, regular expression extensions, and much more.