What is the best practice for iOS SDK refresh token? 

Authentication Method: User Authentication(OAuth 2.0)
SDK: iOS Box SDK
Version: 4.2.0
Custom Token info: Yes

Code:-

if let oAuthSession:OAuth2Session = self.client.session as? OAuth2Session { oAuthSession.refreshToken { result in switch result { case let .success(token): expect(token).to(equal("new access token")) case let .failure(error): fail("refreshToken should succeed, but instead got \(error)") } done() } }

After 24 hours, Refresh token is failing with 401 error code. What is the best practice for iOS SDK refresh token? 

Please guide me.

Thanks,

Prasad