NSManagedObjectContext outside the PersistentDocument - objective-c

Question

I've created a Document Application for Mac OSX to work with CoreDataModel.
Now I'm trying to programmatically save a value in the coredata when a button is clicked.
I'm able to save a value when the app start:
- (void)windowControllerDidLoadNib:(NSWindowController *)aController
{
[super windowControllerDidLoadNib:aController];
NSManagedObjcetContext *moc = [self managedObjectContext];
NSSet *session = [moc fetchObjectsForEntityName:#"Sessions" withPredicate:nil];
NSLog(#"%d", (int)[session count]);
NSManagedObject *obj = [NSEntityDescription insertNewObjectForEntityForName:#"Sessions"
inManagedObjectContext:moc];
[obj setValue:#"TEST" forKey:#"name"];
[obj setValue:[NSDate dateWithTimeIntervalSinceReferenceDate:112700] forKey:#"start"];
[obj setValue:[NSDate dateWithTimeIntervalSinceReferenceDate:118700] forKey:#"stop"];
}
but I want to save a value of a counter inside a NSObject. So I've tried to create a function in the PersistentDocument like the previous passing a value, but the count of the coredata elements is 0, so I think that is not referencing to the correct Entity.
Can anyone explain me how to do that or how this can works?
Thanks
Ale
EDIT:
I'll try to be more clear.
I've a chrono counter with START and STOP button. I want to save the value of the timer, when is stopped, in the coredata using another button SAVE. The managing of the counter is in an NSObject CounterObject.
How can I do it? Now I'm able to write in the core data only from the PersistentDocument caling a function from windowControllerDidLoadNib. I want to call a function that write in the coredata my counter value, but if I call the function in the PersistentDocument from the CounterObject the log that I've inserted show 0 elements instead of 4. So it's not correctly passed.
Here is the code:
// Document
#import "Document.h"
#import "NSManagedObjectContext.h"
#implementation Document
- (id)init
{
self = [super init];
if (self) {
}
return self;
}
- (NSString *)windowNibName
{
// Override returning the nib file name of the document
// If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, you should remove this method and override -makeWindowControllers instead.
return #"Document";
}
- (void)windowControllerDidLoadNib:(NSWindowController *)aController
{
[super windowControllerDidLoadNib:aController];
[self saveTimeMOC:[NSDate dateWithString:#"11:23:34"]];
}
-(IBAction)saveTimeMOC:(NSDate *)time {
NSManagedObjectContext *moc = [self managedObjectContext];
NSSet *session = [moc fetchObjectsForEntityName:#"Sessions" withPredicate:nil];
NSLog(#"%d", (int)[session count]);
NSManagedObject *obj = [NSEntityDescription insertNewObjectForEntityForName:#"Sessions"
inManagedObjectContext:moc];
[obj setValue:#"TEST" forKey:#"name"];
[obj setValue:time forKey:#"start"];
[obj setValue:[NSDate dateWithTimeIntervalSinceReferenceDate:118700] forKey:#"stop"];
}
+ (BOOL)autosavesInPlace
{
return YES;
}
#end
// CounterObject
#import "CounterObject.h"
#import "Document.h"
#implementation CounterObject
#synthesize contText, startButton, stopButton;
-(id)init {
self = [super init];
if (self) {
}
return self;
}
- (IBAction)startContatore:(id)sender {
stopButton.title = #"Stop";
[stopButton setEnabled:YES];
[startButton setEnabled:NO];
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(gestioneTimer) userInfo:nil repeats:YES];
}
- (IBAction)stopContatore:(id)sender {
if (timer != nil) {
[timer invalidate];
timer = nil;
}
if (stopButton.title != #"Reset") {
[startButton setEnabled:YES];
stopButton.title = #"Reset";
startButton.title = #"Continue";
} else if (stopButton.title == #"Reset") {
stopButton.title = #"Stop";
[stopButton setEnabled:NO];
startButton.title = #"Start";
timerCont = 0;
contText.stringValue = [NSString stringWithFormat:#"00:00"];
}
}
- (void)gestioneTimer {
timerCont += 1;
int minutes = floor(timerCont/60);
int seconds = trunc(timerCont - minutes * 60);
contText.stringValue = [NSString stringWithFormat:#"%02i:%02i", minutes, seconds];
}
- (IBAction)saveTime:(id)sender {
Document *moc = [[Document alloc] init];
[moc saveTimeMOC:[NSDate dateWithString:#"13:45:22"]];
}

Answer 1

If you want to add an Object to core data, you can do this :
- (void)windowControllerDidLoadNib:(NSWindowController *)aController
{
[super windowControllerDidLoadNib:aController];
NSManagedObjcetContext *moc = [self managedObjectContext];
// But be sure that [self managedObjectContext] is the correct one; you can do this to see if //it's not a null value : NSLog(#"%#",[self managedObjectContext]);
NSManagedObject *obj = [NSEntityDescription insertNewObjectForEntityForName:#"Sessions"
inManagedObjectContext:moc];
[obj setValue:#"TEST" forKey:#"name"];
[obj setValue:[NSDate dateWithTimeIntervalSinceReferenceDate:112700] forKey:#"start"];
[obj setValue:[NSDate dateWithTimeIntervalSinceReferenceDate:118700] forKey:#"stop"];
}
And a request for Core Data is :
-(voi)testRequestCoreData {
NSError *error =nil;
NSFetchRequest *fetchRequest = [[[NSFetchRequest alloc] init]autorelease];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"Sessions" inManagedObjectContext:moc];
[fetchRequest setEntity:entity];
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
....
}