To use API v2 in iOS platform, we need an objective-C version

First I am a developer and NOT a paid DropBox fanboy ;) You know, I felt the same way at first about the lack of a v2 API for objC. However after integrating the v1 SDK for iOS, and taking a hard look at what "new" or different features are available in the v2 iOS SDK for Swift, there really are no significant features missing.

You are really stressing over the name - v1 vs v2 without considering what the SDK provides or how DropBox really works (under the trappings of any of the SDKs). The core DropBox API is usable by anyone directly using HTTP requests - the interface libraries are just someone's take on making it easier for a given platform or programming language. Furthermore, these libraries (SDKs) are not optimal - NONE of them expose ALL the features of the core DropBox API as it exists as a RESTful interface. They all leave out something you might want or do it in a way which may not fit your desired usage.

What is nice about the DB SDKs is that they are open source and you can enhance them to your liking, use them as is, or roll your own. Also the folks on here are somewhat responsive compared to the other platforms (Drive, iCloud, OneDrive...). The core DB API is much easier to use than any of those other storage APIs as well IMO.

So while I too felt the same way, I have to agree with DropBox - even though they don't say it the iOS v2 SDK does not really bring a lot to the table that the v1 SDK does not bring. And as a developer that has used the v1 SDK, if they were to come out with a v2 SDK for objC, I would be bummed if I had to rewrite a bunch of code for new/different interfaces just to achieve the same functionality I already have today. The only thing I would do to their v1 API is make it Oauth2 compliant and leave everything else the same anyway.