In my case, its because my objectVersion = 70 then i change it into 56 and its works to pod init and pod install.

You can find this objectVersion:

1. Open finder, and open your project folder
2. Find yourProject.xcodeproj
3. Tap with 2 fingers/open the action windows
4. Klik on Show Package Contents
5. Open file project.pbxproj
6. Change objectVersion into 56
7. Save it, then open the terminal and you can try to pod init again