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.
C4 is a creative-coding framework which lets you build expressive user experiences and create works of art on iOS. It gives you the power of the native iOS programming environment with a simplified API which lets you get down to working with media right away. It lets you build artworks, design interfaces, and explore new possibilities of working with media and interaction.
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.
jMonkeyEngine is a game engine made for developers who want to create 3D games following modern technology standards. The framework is programmed entirely in Java, and aimed at wide accessibility and fast deployment to desktop, Web, and mobile platforms. It is not a visual “RPG Maker” or a drag-and-drop “FPS mod”. If you are comfortable writing Java code, you can rely on jMonkeyEngine as your next 3D game’s foundation.