Question

I have some ViewControllers. In the first LoginViewController, where I login, I create newEntity. By clicking on button “Login” I make fetch and assign for this newEntity fetch by predicate “login”. AppDelegate.h have create things for Core Data. In LoginViewController I have next strings in .h:

@class AppDelegate;
...
@property (strong, nonatomic) AppDelegate *appMeDelegate;
@property (strong, nonatomic) NSManagedObjectContext *context;
...

In LoginViewController.m

#import "AppDelegate.h"
...
@synthesize ... appMeDelegate, context;
...
//I have login button where i compare login and password in 
//UITextFields with that in Core Data and if it is 
//all right i load fetch for user with his login
-(IBAction)login:
{
appMeDelegate = (AppDelegate *) [[UIApplication sharedApplication]delegate];
context = appMeDelegate.managedObjectContext;
NSFetchRequest * fetchRequest = [[NSFetchRequest alloc]init];
NSPredicate *predicateMe = [NSPredicate predicateWithFormat:@"login==%@",login.text];
fetchRequest.predicate = predicateMe;
... //then I create newEntity }
//next method for saving
-(void)saving
{
NSError *error = nil;
if (![context save:&error]) {
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}}

And then in other ViewController i use newEntity but can not save it

- (void)viewDidLoad
{
[super viewDidLoad];
NSData *newdata = [NSData dataWithData:self.loginViewController.newEntity.photo];
photoArray = [NSMutableArray arrayWithArray:
[NSKeyedUnarchiver unarchiveObjectWithData:newdata]];}

-(IBAction)save
 {  [photoArray addObject:myImage];
NSData *newData = [NSKeyedArchiver archivedDataWithRootObject:photoArray];
[self.loginViewController.newEntity setValue:newData forKey:@"photo"];
[self.loginViewController saving];

But no results and it didn’t save changing in entity

Answer 1

You would use something like this to save your managedDocument context

    [self.managedDocument saveToURL: self.managedDocument.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) {
    if (completionHandler) completionHandler(success);
}];

EDIT
Sorry, just saw you are obviously not using an NSManagedDocument (which you should look into).

Dont do this:

[self.loginViewController saving];

Do it like you did before:

appMeDelegate = (AppDelegate *) [[UIApplication sharedApplication]delegate];
NSManagedObjectContext *context = appMeDelegate.managedObjectContext;
[context save: &error];