Xcode and Backendless connection problem

When starting my app in Xcode simulator, build succeed but the following message appears: Connection problems, Load again.

Maybe I skipped a step when migrating from Parse.
-I imported the datas files
-I changed my App ID and Client ID in Xcode

Can you tell what I missed during my migration?
Regards

Hi Elisa,
Could you provide some screenshots demonstrating the problem?