iOS retrieving access_token from OktaAuth.tokens on second load?

New to OktaAuth in my ios app. Have implemented the basic login example from documentation.

After login it sets the accessToken
OktaAuth.tokens?.set(value: tokenResponse.accessToken!, forKey: “accessToken”)

I can immediately access it from the app using this.
OktaAuth.tokens?.get(forKey: “accessToken”)

However, the next time I load the app the OktaAuth.tokens is nil, and the “session” requires login again. Is there a proper way to reload tokens from keychain? My goal is to reopen the app and not to have to login again.