Objective C - No know class method for selection

Question

I'm trying to implement a database system where an entity contains some methods in its DataClass.m but I cannot call them in my ViewController.m

In the code above I try to call savePersona but the build says

No known class method for selector 'savePersona:etaLabel:indirizzoLabel:contextLabel:'

ViewController.m

#import "ViewController.h"
#import "Giovanni+CoreDataClass.h"
#import "AppDelegate.h"


@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
}

/*
 * Event after clicking button Save.
 */
- (IBAction)btnSave:(id)sender {
    NSString *nome = _insertName.text;
    NSString *eta = _insertAge.text;
    NSString *indirizzo = _insertIndirizzo.text;

    // Check for all inputs
    if ([nome isEqualToString:@""] || [eta isEqualToString:@""] || [eta intValue] <= 0 || [indirizzo isEqualToString:@""] ) {
        _resultText.text = @"All fields are required";
        return;
    }


    [Giovanni savePersona:nome etaLabel:[eta intValue] indirizzoLabel:indirizzo contextLabel:[((AppDelegate *)[[UIApplication sharedApplication] delegate]) managedObjectContext]];
}

Giovanni+CoreDataClass.h

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@interface Giovanni : NSManagedObject

+(void)savePersona: (NSString*)nome etaLabel:(int16_t)eta indirizzoLabel:(NSString*)indirizzo contextLabel:(NSManagedObjectContext *)context;

@end

#import "Giovanni+CoreDataProperties.h"

Giovanni+CoreDataClass.m

#import "Giovanni+CoreDataClass.h"

@implementation Giovanni

+(void)savePersona: (NSString*)nome etaLabel:(int16_t)eta indirizzoLabel:(NSString*)indirizzo contextLabel:(NSManagedObjectContext *)context {
    Giovanni *p1 = [[Giovanni alloc] initWithContext:context];
    p1.nome = nome;
    p1.eta = eta;
    p1.indirizzo = indirizzo;
}

In Build Phases I have Giovanni+CoreDataClass.m and Giovanni+CoreDataProperties.m. In Copy Bundle Recources I have DatabaseExample.xcdatamodeld (DatabaseExample is the name of the project)

Answer 1

I have resolved my problem by recreating the project.

Nothing has changed but it seams that XCode encounter some problems on autocreating my entities when i click on Editor -> Create NSManagedObject Subclasses...

I don't know if it's a bug of the latest versione but now the project works fine.