This start-over implementation on Injection for Xcode has been built into an app: InjectionIII.app included in the repo which runs in the status bar. Code injection allows you to update the implementation of methods of a class incrementally in the iOS simulator without having to rebuild or restart your application saving developer time. You can avoid the complications of code signing by using the pre-built binary which is available to download here. For some reason you may need to take the app out of qurantine manually or it will report it as damaged when you run it: xattr -d com.apple.quarantine ~/Downloads/InjectionIII.app. To use, copy/link it to /Applications and run the app. Injection also expects to find your current Xcode at path /Appplications/Xcode.app. Injection no longer requires you to change your project as for iOS is always available if you use the "Start Injection" menu (or type control-=) each time you start your app. Once injection is connected, a file watcher is started in the InjectionIII app and whenever you save a Swift or Objective-C source the target app is messaged to update the implementation. The file watcher can be disabled & enabled while the app is running using the status bar menu. If you inject a subclass of XCTest it will try running that individual test inside your application. When you run your application without rebuilding (^⌘R), recent injections will be re-applied.