JSON? Wrong way Corrigan.
If you are getting this from a third party, you have no other option but to go line by line and see what has changed. It's a CSV. You can expect it to be corrupt. You will need to handle that. It isn't all that difficult. Write a script to import the CSV. In your script, you can automate the data integrity checks. That will tell you if you are missing data. But you must do this yourself. You can't rely on some 3rd party tool. Such tools often just throw out invalid data. I assume that isn't what you want.
I can guarantee the data isn't originally in CSV. (Well, that's a lie. I can't guarantee that. I've seen some monumentally stupid things.) Let's say the data probably isn't originally in CSV. That means two things. You might be able to get the data in a more stable, more easily parsed format. Ask. It also means that the source data could have content that isn't CSV-friendly. Funky Unicode perhaps? How well would you handle Arabic in that CSV?
But if this is the best there this, then you'll have to made do. Write a parser and validator. Emit content that your app can easily read. You really don't want something like JSON. That just has to be re-parsed again. SQLite is super easy. When you load it in your app, your parse time is 0 ms.
I know what you are thinking. Stop right there. You don't want to use Core Data. Just stuff the data in a dead-simple SQLite table. Add some indexes. You can extract the data with very little effort.