
| Name | Description | Type | Use | 
|---|---|---|---|
| callback | A JavaScript object, as described below. | object | 
          required | 
The getCredentials method's callback object can be structured as
      follows:
{
  onSuccess: function(credentials) { ... },
  onFailure: function({code, description}) { ... }
}| Name | Description | Return type | 
|---|---|---|
| onSuccess | This method is called after credentials are successfully saved in the keychain. | undefined | 
        
| onFailure | This method is called if the process fails. It passes the error object with two
            properties: code, which contains an error code, and
              description, which contains a human-readable error
            description. | 
          undefined | 
        
The Credentials object can be structured as follows:
{
  identifier,
  password
}Where:
identifier stands for a user identifier,
password stands for a user password connected with the
            identifier.