How do I check if the user has already registered before?

iOS
1

Hi,
Is there any method which can tell me if a particular email address has been registered or not?
I need this information to check if a Google plus user is using the same email address a as facebook user and try and combine both.
Also I have some custom user properties that get updated everytime I press the login with facebook method. (I’m using the same button for Sign-up and subsequent logins)
So what is the best way to go about checking the entire database for existing registrations?
iOS- Objective C.
Thank you

2

To see if a user has registered before you can perform data retrieval from the Users table:

        let query = BackendlessDataQuery()
        let userEmail = "foo@foo.com"
        query.whereClause = "email = '\(userEmail)'"
        let users = backendless.data.of(BackendlessUser.ofClass()).find(query)
        
        if( users.data.count > 0 )
        {
            // user exists
        }
3

Could you also give me a Objective-C version of this.

Actually line 3 & 4 is all I need.

Thanks.

4

Obj-C is not my forte… Please see the API/examples on this page:

https://backendless.com/documentation/data/ios/data_search_and_query.htm

Mark

5

Is it ok to use collections and persistence service like in your examples? I’m getting the result I need.









 BackendlessCollection *collection = [backendless.persistenceService find:[BackendlessUser class] dataQuery:query];

I’m asking this because I cant find those terms in the swift code you pasted above.
Trying to make sure its the best option available.

Thanks

6

Yes, this is totally fine. You might also want to set queryOptions.pageSize = 1 to minimize the payload, since all you need to know if there is a user or not.