There's no magic to Xcode, j2objc, or iOS development: if a project points to a path that doesn't exist, the build will fail. Once that path is fixed and/or the missing file(s) are installed, the build will work. If you've never worked with command-lines before, find a tutorial.
"J2ObjC_source.h' file not found":
- Open your project's System.config file, and copy what J2OBJC_HOME is set to.
- In a Terminal window, type "ls " and paste in the path you copied. You should see the same list of files I posted previously: BUILD, LICENSE, WORKSPACE, etc.
- If you don't see the same file set, fix your path so it points to the correct place you unzipped the j2objc-2.7.zip file.
- Don't use "~" in System.config, use the actual path. To see what that is, run "cd && pwd".
- Type "ls ", that J2OBJC_HOME path you copied, and "/include". You should see J2ObjC_source.h listed.
- If you don't, delete the whole J2OBJC_HOME path, unzip the j2objc-2.7.zip file again, and try again.
- In your Xcode project, bring up the project settings and click the Build Settings panel.
- Search for Header Search Paths. It should be "${J2OBJC_HOME}/include"; if not, fix it.
- In Framework Search Paths, add "${J2OBJC_HOME}/frameworks"
- In Other Linker Flags, add "-liconv" (needed for locale conversion).
If none of this works, give up (seriously). j2objc is designed for very large, cross-platform apps, which are generally created by teams of experienced software engineers. For small apps, it is both easier and faster to rewrite the app from scratch, sharing only the app's design and resources but no code. j2objc should never be a way for Android developers to avoid learning iOS development, as that's a disservice to the app's users.