I followed the way as you mentioned. But the problem is sending data from app to website. I tried to submit form to external link, But since I can send data only in json format sending data to payment gateway was not possible.
I have something link this,
On submitting this form, It should send values to www.example.com/api. Making this happen in angularjs is little tough. I used $http.post to send data. But it sends in json format, Payment gateway is not accepting the values.