iOS: How can I authenticate via dropbox app?

We don't currently have any documentation for the app authorization flow built in to the official Dropbox mobile apps, but I'll be sure to pass this along as a request for that.

That flow is handled for you in the SDKs, but if you're not using one of the SDKs, you'll need to use an OAuth 1 or OAuth 2 flow instead:

OAuth 1:

https://www.dropbox.com/developers/core/docs#request-token
https://www.dropbox.com/developers/core/docs#authorize
https://www.dropbox.com/developers/core/docs#access-token

https://blogs.dropbox.com/developers/2012/07/using-oauth-1-0-with-the-plaintext-signature-method/

OAuth 2:

https://www.dropbox.com/developers/core/docs#oa2-authorize
https://www.dropbox.com/developers/core/docs#oa2-token

https://blogs.dropbox.com/developers/2013/07/using-oauth-2-0-with-the-core-api/

Thanks for quick reply
at the moment, I'm using oauth to authorization via safari and it's work fine, but I guess you understand that for it my customers need to fill form instead just a one tap to authorize. Anyway can I use the flow from Dropbox SDK to get authorization via app? (not using Dropbox SDK, just the using the same aproach) ?

You could replicate what the SDK does, though it'd be safer to just use the standard OAuth flow, since the SDK flow isn't documented.

By the way, on iOS, if you use an OAuth flow, make sure to use the disable_signup parameter to comply with Apple's guidelines.

Got it, thanks for advice