PersistentDocument之外的NSManagedObjectContext

Question

我已經爲Mac OSX創建了一個文檔應用程序來處理CoreDataModel。

現在我試圖以編程方式在單擊按鈕時將值保存在coredata中。

我能夠保存的值時，應用程序啓動：

- (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"]; 
} 

但我要救一個NSObject的內部計數器的值。所以我試圖在PersistentDocument中創建一個像前面傳遞值一樣的函數，但是coredata元素的計數是0，所以我認爲這不是引用正確的實體。

任何人都可以解釋我如何做到這一點或如何這可以工作？

感謝 啤酒

編輯：

我會試着更清楚。

我有一個帶START和STOP按鈕的計時器。我想用另一個按鈕SAVE保存計時器的值，當它停止時，在coredata中。計數器的管理位於NSObject CounterObject中。

我該怎麼辦？現在，我只能通過PersistentDocument從windowControllerDidLoadNib中調用函數來寫入核心數據。我想調用一個函數，在coredata中寫入我的計數器值，但如果我從CounterObject調用PersistentDocument中的函數，我插入的日誌顯示0個元素而不是4個，因此它沒有正確傳遞。

下面是代碼：

// 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

如果你想添加一個對象到核心數據，你可以這樣做：

- (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"]; 
} 

而對於核心數據的請求是：

-(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]; 
.... 
}