Sign In via access token without login page

[Cross-linking for reference: https://stackoverflow.com/questions/42622883/swifty-dropbox-sign-in-via-access-token ]

The API was designed with the intention that each user would link their own Dropbox account, in order to interact with their own files. However, it is technically possible to connect to just one account. The SDKs don't offer explicit support for it and we don't recommend doing so, for various technical and security reasons.

However if you did want to go this route, instead of kicking off the authorization flow, you would manually use an existing access token for your account and app, as you're trying to here. (Just be careful not to revoke it, e.g. via https://www.dropbox.com/account/security .)

As far as the actual issue you're running in to, I suspect the issue is that you're constructing the client object and making the call, but then the client object is going out of scope before the response can come back. Make sure you keep your client object around. For example, you can use authorizedClient to store it, like this:

DropboxClientsManager.authorizedClient = DropboxClient.init(accessToken: "...")

And then use the client via DropboxClientsManager.authorizedClient.