Ionic application from androidi to iOS



I developped a ionic application on my Linux PC for android platform. This application gets data from a server with REST requests. It’s working fine on my android smartphone.
Now, I would like to move this application on iOS. I have a Mac mini and I copied the application on this. I added the iOS platform and run the application on the simulator. The first screen of my application is a login screen. The screen appears and I type the login/password and the $http function returns an error with response=’’ and status=0
How to debug it ? what is the problem ?
Thank you for your advice.