Without having the actual project, it is very difficult to tell what the problem is. However, you do have a problem with the code that you have written. This won't compile with the data/string/JSON variable being declared. That "may" be the actual problem. Please try the following and see if that helps.
I solved this issue by changing the Build Active Architectures Only settings.
Click on your project in the Project Explorer, select Build Settings, locate Architectures section, and change the Build Active Architecture Only setting to Yes for Debug and No for Release.
I had the same problem after installing from cocoapods.
Choosing Product | Clean then Product | Build fixed it.
I selected my project name then the project then.
- Clean Cmd+shit+K
- Build Cmd+B
Strangely enough this worked for me. Good Luck!