Updating Core Data fail - ios

Question

-(void)passDataBack:(PersonHolder *)contact{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"Person"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"firstName == %#",contact.firstName];
[request setPredicate:predicate];
NSError *error;
Person *person = [[self.managedObjectContext executeFetchRequest:request error:&error]lastObject];
[person.firstName setValue:contact.firstName forKey:#"fistName"];
[person.lastName setValue:contact.lastName forKey:#"lastName"];
if(![self.managedObjectContext save:&error]){
NSLog(#"Could not save edited data");
}
}
during runtime I can see that contact is loaded with all the data I'm passing through but my person entity is not getting updated.
I saw the answer how to update core data entered values and I think I am certainly missing something

Answer 1

You don't missing something, quite the contrary
The Core Data equivalent to the simple property setter
person.firstName = contact.firstName
is
[person setValue:contact.firstName forKey:#"firstName"];
[person setValue:contact.lastName forKey:#"lastName"];
consider also the typo #"fistName"
Edit: Try this syntax
NSArray *people = [self.managedObjectContext executeFetchRequest:request error:&error];
if (error) {
NSLog(#"%#", error);
return;
}
if (people.count) {
Person *person = [people lastObject];
person.firstName = contact.firstName;
person.lastName = contact.lastName;
if(![self.managedObjectContext save:&error]){
NSLog(#"Could not save edited data");
}
} else {
NSLog(#"result array is empty"):
}

Answer 2

Instead of
[person.firstName setValue:contact.firstName forKey:#"firstName"];
[person.lastName setValue:contact.lastName forKey:#"lastName"];
use
[person setValue:contact.firstName forKey:#"firstName"];
[person setValue:contact.lastName forKey:#"lastName"];
or
person.firstName = contact.firstName;
person.lastName = contact.lastName;
Edit : a suggestion before blindly assigning last object of fetch query to person object and setting values in core data, check if your fetch query returns a result or not. This may crash.
NSArray *persons = [[[CoreDataManager sharedManager] context] executeFetchRequest:fetchRequest error:&error];
if(persons.count > 0){
// do changes in the object
}
else{
// do what you want to do to handle this situation
}