Two different Entry relationship in core data - iphone

Question

I am using core data with two different entieties
userinformation. - firstname ,lastname , city etc
phonenumber - number
user information and phone number between i have given To many realtionship
-(NSArray*)getAllPhoneBookRecords
{
// initializing NSFetchRequest
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
//Setting Entity to be Queried
NSEntityDescription *entity = [NSEntityDescription entityForName:#"userinformation"
inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSError* error;
// Query on managedObjectContext With Generated fetchRequest
NSArray *fetchedRecords = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
for (NSManagedObject *info in fetchedRecords)
{
NSLog(#"city name: %#", [info valueForKey:#"city"]);
NSLog(#"first name: %#", [info valueForKey:#"firstName"]);
NSLog(#"Last name: %#", [info valueForKey:#"lastName"]);
NSLog(#"first phonenumber is %#",[info valueForKey:#"number"]);
}
and I have calling this method
AppDelegate* appDelegate = [UIApplication sharedApplication].delegate;
self.managedObjectContext = appDelegate.managedObjectContext;
self.fetchedRecordsArray = [[appDelegate getAllPhoneBookRecords]mutableCopy];
but it is show only first table data and than it come
NSLog(#"first phonenumber is %#",[info valueForKey:#"number"]);
it is showing Terminating app due to uncaught exception 'NSUnknownKeyException', reason:
'[<userinforamtion 0x84691b0> valueForUndefinedKey:]: the entity userinforamtion is not key value coding- compliant for the key "number
but in phonenumber entity i have taken attribute for number
Am i doing the wrong realtionship between user inforamtion and phonenumber ?

Answer 1

First, entity names are usually CamelCase. The core data model editor even enforces that, so you are already lucky your code does not crash right there.
Second, you should have Xcode create custom classes and use their accessors. That is exactly the way to prevent undefined key errors. You would set and access the attributes like this (also much more readable):
NSLog (#"Last name: %#", info.lastName);
info.lastName = #"Doe";
Third, you should be clear what you are accessing via the relationship. The relationship itself points to an instance of another entity. To get to that entities property you have to go another step.
PhoneNumber *phoneNumber = [info.numbers anyObject];
NSLog(#"Some phone number: %#", phoneNumber.number;
Finally, make sure your attribute and relationship names are correct. E.g. if you have a to-many relationship to phone numbers, the Info relationship to PhoneNumber should appropriately be called numbers. The order of numbers is not determined, so you don't know which is the "first".
Maybe you want to look into the possibility to use the ABAddressBook instead for your purposes.