Ionic Cordova API Authorisation 401

Ionic application developed in angular 9 combination.

While Authenticating API using header value, application working fine in Android and Web. Same code not working in iOS and giving 401 error.

First i have tried with import { HttpClient, HttpErrorResponse, HttpHeaders, HttpParams } from '@angular/common/http';

Worked in Web and Android, not worked in iOS, In iOS getting 401 error.

Then i integrated import { HTTP } from '@ionic-native/http/ngx'; and tried API call same result.

401 error