Can I authenticate user using adal for iOS (https://github.com/AzureAD/azure-activedirectory-library-for-objc) without webview being popped up ? Is there some API to which I can provide username/password and it returns me auth-token without user typing credentials ?
No. Adal on mobile platforms does not provide mechanisms for using raw username and password directly. Once you performed the interactive authentication (and consent, mfa or anything else your azure ad settings require) you'll be able to function for a long time without prompting again, but that first step requires an experience that offers the opportunity to inject those extra steps. Also, this makes it possible to never disclose credentials directly to the app.