Using Parse and AWS Cognito

I'm using Parse as my backend but I'm also using the AWS s3 service so I need to also use Amazon Cognito. So far Amazon Cognito integrates with 3rd party identity providers such as Facebook, Google, and Twitter but not Parse. So I'm guessing I would use the Basic flow which

"Uses Cognito + STS and requires identity pool plus IAM roles"

http://ift.tt/1I7yT9L

since I'm using Parse as my backend I won't be able to use the Developer authenticated identities method. But I'm not entirely sure.

But my only issue is how I could get session tokens for temporary AWS Service access for users? Most of the tutorials/blogs I find online explain how to access the tokens on the server side but not on ios unless I'm missing a crucial concept here