ios - AWSCognitoIdentityUser getSession not called -

i'm trying idtoken awscognitoidentityuser continue block never called. cause of this?

awscognitoidentityuserpool *pool = [awscognitoidentityuserpool cognitoidentityuserpoolforkey:@"userpool"]; awscognitoidentityuser *user = [pool currentuser];  [[user getsession] continuewithblock:^id _nullable(awstask<awscognitoidentityusersession *> * _nonnull task) {     //never called     return nil; }]; 

first turn on verbose logging: [awslogger defaultlogger].loglevel = awsloglevelverbose; determine error is.

sounds have associated awscognitoidentityinteractiveauthenticationdelegate pool.

is startpasswordauthentication method getting called? correctly returning implementation of awscognitoidentitypasswordauthentication , setting passwordauthenticationcompletionsource.result instance of awscognitoidentitypasswordauthenticationdetails in implementation of getpasswordauthenticationdetails