Do we have to use Cognito for Dynamodb access?

Upgrading some legacy code using the old SDK, I would access dynamoDB using an AWS_KEY and Secret_KEY packaged in credentials that were then given to an AWSDynamoDbClient object. In version 2.0 of the SDK this client object is no longer available in AWSDynamoDB.h. All the documentation now points to Cognito for authentication so is the old way of access deprecated and the Keys not used anymore?