Make changes in already developed Android and iPhone application

Please read the project description carefully before bidding on this project. Skills required: iOS Development(Swift), Android, PHP, Virtual Private Servers, Facebook API. *Make sure you bid the correct price and please do not change the price in the chat* 1. Virtual Private Server knowledge required. I have the backend files, you have to upload them to VPS and connect that server to Android and iOS app. 2. Facebook login and other setup related to facebook is done. I lost the credentials of that facebook account. So, you don't need to change the code. Just I will give another FB Developer account. It should work normally as before(login, pic sharing to facebook, data retrieving)-[All this code is already implemented]. [login to view URL] UIalert to the user asking to rate the app. [login to view URL] iRate 4. Assume a user A who is having phone1 and phone2. When this user is logged in(only FB login is available) with phone1 his details are stored in the database. If he make any changes in his profile, like, change name, DOB, profile pic etc they are changing in this phone and updating in the database. But, if this same user is logged in with this same facebook account in phone2 it is storing this as new user in the database, if any changes in phone2 are made then they are not updating in phone1. The possible reason for this problem is, in login screen there are two buttons 1. Guest user 2. Facebook login. For 1 I am using Core data to store the information in the phone posted by the guest. When a guest is logged in a unique id is created, this id differs from phone to phone. Guest can create, edit and delete the information he has posted. So, this is the reason for above mentioned problem. This problem needs to be solved. One user, in whatever phone he logs in he should continue his app like before and new user should not be created in the database. i.e., When we use any app or website, if we once create an account we can use it in any device by logging in. If I am not clear, I will explain again clearly in chat. Please ask me. *This should work in future updates of both operating systems* Please read it carefully and bid on this project. I cannot afford much, so please make sure your bid is low cost as possible. I have another project if this is done completely well then surely within completion of this project I will give you that project. Thank you.