Getting username after authentification with coredata predicate - ios

Question

I am a beginner in Xcode. I would like to get the username or the ID after the user enters their login and password in textfield. I am sure I am doing wrong.
My code bug is after the access granted.
app due to uncaught exception
'`NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]:
object cannot be nil`'
Here is my code:
- (IBAction)stepInButton:(id)sender {
AppDelegate *appDelegateCoreData = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegateCoreData managedObjectContext];
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:#"Player" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDesc];
NSPredicate *pred = [NSPredicate predicateWithFormat:
#"(playerlogin = %#) AND (playerpassword =%#)", self.loginTextField.text, self.passwordTextField.text];
[request setPredicate:pred];
NSError *error;
NSArray *objects = [context executeFetchRequest:request error:&error];
if ([objects count] == 0) {
self.loginStatusLabel.hidden = NO;
NSLog(#"LOGIN IN ACCESS DENIED");
} else {
NSLog(#"LOGIN IN ACCESS GRANTED");
NSExpression *keyPathExpression = [NSExpression expressionForKeyPath:#"playerfirstname"];
NSExpressionDescription *expressionDescription = [[NSExpressionDescription alloc] init];
[expressionDescription setExpression:keyPathExpression];
[expressionDescription setExpressionResultType:NSDateAttributeType];
[request setPropertiesToFetch:[NSArray arrayWithObject:expressionDescription]];
NSError *error;
NSArray *objects = [context executeFetchRequest:request error:&error];
if ([objects count] == 0) {
// Handle the error.
}
else {
if ([objects count] > 0) {
NSString *playerFirstName = [[objects objectAtIndex:0] valueForKey:#"playerfirstname"];
NSLog(#"PlayerFirstName: %#", [[objects objectAtIndex:0] valueForKey:#"playerfirstname"]);
self.welcomePlayerLabel.text = [NSString stringWithFormat: #"Welcome %#", playerFirstName];
}
}
self.loginStatusLabel.hidden = YES;
self.signButton.hidden = YES;
self.stepButton.hidden =YES;
self.loginStatusLabel.text =(#"Access Granted");
self.loginStatusLabel.textColor = [UIColor greenColor];
self.loginStatusLabel.hidden = NO;
//FirstViewController *firstViewController = [[FirstViewController alloc] init];
//[self.navigationController pushViewController:firstViewController animated:YES];
//[self.navigationController pushViewController:[self.storyboard instantiateViewControllerWithIdentifier:#"first"] animated:YES];
}
}

Answer 1

ok I got it.
I retieved the playerFirstName directly form object like Dan Shelly said. Thanks you Dan.
- (IBAction)stepInButton:(id)sender {
AppDelegate *appDelegateCoreData = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegateCoreData managedObjectContext];
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:#"Player" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDesc];
NSPredicate *pred = [NSPredicate predicateWithFormat:
#"(playerlogin = %#) AND (playerpassword =%#)", self.loginTextField.text, self.passwordTextField.text];
[request setPredicate:pred];
NSError *error;
NSArray *objects = [context executeFetchRequest:request error:&error];
if ([objects count] == 0) {
self.loginStatusLabel.hidden = NO;
NSLog(#"LOGIN IN ACCESS DENIED");
} else {
NSLog(#"LOGIN IN ACCESS GRANTED");
NSString *playerFirstName = [[objects objectAtIndex:0] valueForKey:#"playerfirstname"];
self.welcomePlayerLabel.text = [NSString stringWithFormat: #"Welcome %#", playerFirstName];
self.loginStatusLabel.hidden = YES;
self.signButton.hidden = YES;
self.stepButton.hidden =YES;
self.loginStatusLabel.text =(#"Access Granted");
self.loginStatusLabel.textColor = [UIColor greenColor];
self.loginStatusLabel.hidden = NO;
}
}