nst/runtimebrowser

RuntimeBrowser is a development tool for iOS and macOS that lets you browse all the Objective-C classes that are loaded and running on a device at any given moment. Objective-C is the older Apple programming language that underlies much of iOS and macOS, and the "runtime" is the system that manages classes, methods, and objects while an app is active. This tool gives you a live window into that system. On iOS, you can navigate classes organized by tree, image, or a flat indexed list, and search by class name. The tool can retrieve header files over a local HTTP connection on port 10000. It can also create instances of most classes and invoke methods on them at runtime, including passing in parameters. This is useful for developers who want to understand how Apple's internal or undocumented APIs work, or who are exploring the internals of a third-party framework. The macOS version adds syntax colorization, the ability to search inside class contents rather than just names, and support for browsing by protocols in addition to class trees. You can drag and drop frameworks and header files directly into the browser to inspect them. A prebuilt download for macOS is linked from the README. Both versions display information in the standard Objective-C header file format, the same style any iOS or macOS developer would recognize. The project has been maintained since 2008 and originated in 2002. A companion repository called iOS-Runtime-Headers shows a snapshot of iOS headers as seen through this tool. The README notes that each user is responsible for their own use of the tool, given its ability to inspect internal class structures.