Question

I am having trouble fetching a row with specific conditions.

I have an Entity called UserAccounts that it contains four attributes: userName, passWord, userFullName, userLevel.

For login, I have to get a passWord that matches the userName. To do this I have two text fields, userNameTF and passWordTF.
I have to fetch a row with an entity (I am using SQL to compare my request) that matches the userNameTF.stringValue and then check if the passWord attribute is equal to passWordTF.stringValue.

Right now I can take arrays of userName and passWord from my Core Data store separately using:

NSArray *userName = [[userAccountsArray arrangedObjects] valueForKey:@"userName"];   
NSArray *passWord = [[userAccountsArray arrangedObjects] valueForKey:@"passWord"];

but these two arrays have no relation to each other, and I can’t compare the password with entered username.

I done this before by SQL in VisualStudio using: select "password" from userAccounts where userName = @"username" and then comparing the result with the entered password, but I can’t find a way to fetch a row with an entity, to do something with its attributes.

Answer 1

Well, Finally I found a way solving my problem AGAIN !

Using this code I can retrieve whole attributes of an Entity’s record regarding one specific attribute’s value.

NSArray *userAccounts=[userAccountsArray arrangedObjects]; 
NSArray *matchingAccounts=[userAccounts  filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"%K == %@",@"userName",userNameTF.stringValue]];
NSString *matchedPassWords=[[matchingAccounts valueForKey:@"passWord"]objectAtIndex:0];

So I can find the passWord related to userName that user typed in the userNameTF textfield !

Anyway, this is my way to solve the problem and I think there is more solutions out there.

Thank you all.