Objective c 更新核心数据中的managedObject

到目前为止我拥有的：

if ([_sessionData.added isEqualToNumber:[NSNumber numberWithBool:NO]]) {

    [_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

    NSManagedObjectContext *moc = [[DataSingleton sharedMySingleton] managedObjectContext];

    SessionData *session = (SessionData*) [NSEntityDescription insertNewObjectForEntityForName:@"NewSessions" inManagedObjectContext:moc];

    session.startDate = _sessionData.startDate;
    session.endDate = _sessionData.endDate;
    session.sessionLocation = nil;
    session.sessionTitle = _sessionData.sessionTitle;
    session.sessionDescription = _sessionData.sessionDescription;
    session.added = [NSNumber numberWithBool:YES];

    _addButton =  [[[UIBarButtonItem alloc] initWithTitle:@"Remove" style:UIBarButtonSystemItemAdd target:self action:nil] autorelease];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveMoc:) name:NSManagedObjectContextDidSaveNotification object:moc];

    NSError *error = nil;

    if (![moc save:&error]) {
        DebugLog(@"Whoops, couldn't save:%@", [error localizedDescription]);
    }

} else {
    NSLog(@"SESSION ALREADY ADDED");
}

在一个splitview中，我有一个tableview作为其主视图，一个UIView作为详细视图。tableview有两列：“天”和“会话”。我从核心数据中获取数据，这些数据被称为“会话”。当我单击“会话”tableviewcell时，detailview会更新

在detailview中，我在导航栏中添加了一个“Add”按钮。当您单击此按钮时，我将向核心数据添加一个名为“NewSession”的新实体

if ([_sessionData.added isEqualToNumber:[NSNumber numberWithBool:NO]]) {

        [_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

    SessionData *session = (SessionData*) [NSEntityDescription insertNewObjectForEntityForName:@"NewSessions" inManagedObjectContext:[DataSingleton sharedMySingleton].managedObjectContext];

    session.startDate = _sessionData.startDate;
    session.endDate = _sessionData.endDate;
    session.sessionLocation = nil;
    session.sessionTitle = _sessionData.sessionTitle;
    session.sessionDescription = _sessionData.sessionDescription;
    [session setValue: [NSNumber numberWithBool:YES] forKey:@"added"];

    _addButton =  [[[UIBarButtonItem alloc] initWithTitle:@"Remove" style:UIBarButtonSystemItemAdd target:self action:nil] autorelease];
    NSError *error = nil;

            if (![[DataSingleton sharedMySingleton].managedObjectContext save:&error]) {
                DebugLog(@"Whoops, couldn't save:%@", [error localizedDescription]);
            }
    }
    else {
        NSLog(@"SESSION ALREADY ADDED");
    }

另一个splitview的tableview获取“NewSession”实体，获取并显示所有数据

问题：

if ([_sessionData.added isEqualToNumber:[NSNumber numberWithBool:NO]]) {

    [_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

    NSManagedObjectContext *moc = [[DataSingleton sharedMySingleton] managedObjectContext];

    SessionData *session = (SessionData*) [NSEntityDescription insertNewObjectForEntityForName:@"NewSessions" inManagedObjectContext:moc];

    session.startDate = _sessionData.startDate;
    session.endDate = _sessionData.endDate;
    session.sessionLocation = nil;
    session.sessionTitle = _sessionData.sessionTitle;
    session.sessionDescription = _sessionData.sessionDescription;
    session.added = [NSNumber numberWithBool:YES];

    _addButton =  [[[UIBarButtonItem alloc] initWithTitle:@"Remove" style:UIBarButtonSystemItemAdd target:self action:nil] autorelease];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveMoc:) name:NSManagedObjectContextDidSaveNotification object:moc];

    NSError *error = nil;

    if (![moc save:&error]) {
        DebugLog(@"Whoops, couldn't save:%@", [error localizedDescription]);
    }

} else {
    NSLog(@"SESSION ALREADY ADDED");
}

每当我退出应用程序并重新启动它时，另一个splitview中的会话仍然存在，但我可以再次添加相同的会话

在“添加”代码中，我有以下内容：

[_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

现在，我的sessionData是一个NSManagedObject；我认为只要设置这些值，就会在核心数据中更新它们

if ([_sessionData.added isEqualToNumber:[NSNumber numberWithBool:NO]]) {

        [_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

    SessionData *session = (SessionData*) [NSEntityDescription insertNewObjectForEntityForName:@"NewSessions" inManagedObjectContext:[DataSingleton sharedMySingleton].managedObjectContext];

    session.startDate = _sessionData.startDate;
    session.endDate = _sessionData.endDate;
    session.sessionLocation = nil;
    session.sessionTitle = _sessionData.sessionTitle;
    session.sessionDescription = _sessionData.sessionDescription;
    [session setValue: [NSNumber numberWithBool:YES] forKey:@"added"];

    _addButton =  [[[UIBarButtonItem alloc] initWithTitle:@"Remove" style:UIBarButtonSystemItemAdd target:self action:nil] autorelease];
    NSError *error = nil;

            if (![[DataSingleton sharedMySingleton].managedObjectContext save:&error]) {
                DebugLog(@"Whoops, couldn't save:%@", [error localizedDescription]);
            }
    }
    else {
        NSLog(@"SESSION ALREADY ADDED");
    }

---

有人能帮忙吗？

我也有类似的问题，但相似并不意味着相同。我不知道这对你是否有效，但你可以试试。@macbirdie向我描述了这种方法，它对我很有效

首先，导入AppDelegate头文件：

#import "YourAppDelegate.h"

- (void)saveMoc:(NSNotification *)notification {
    YourAppDelegate *appDel = (YourAppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDel.managedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}

然后，更新您的代码：

if ([_sessionData.added isEqualToNumber:[NSNumber numberWithBool:NO]]) {

    [_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

    NSManagedObjectContext *moc = [[DataSingleton sharedMySingleton] managedObjectContext];

    SessionData *session = (SessionData*) [NSEntityDescription insertNewObjectForEntityForName:@"NewSessions" inManagedObjectContext:moc];

    session.startDate = _sessionData.startDate;
    session.endDate = _sessionData.endDate;
    session.sessionLocation = nil;
    session.sessionTitle = _sessionData.sessionTitle;
    session.sessionDescription = _sessionData.sessionDescription;
    session.added = [NSNumber numberWithBool:YES];

    _addButton =  [[[UIBarButtonItem alloc] initWithTitle:@"Remove" style:UIBarButtonSystemItemAdd target:self action:nil] autorelease];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveMoc:) name:NSManagedObjectContextDidSaveNotification object:moc];

    NSError *error = nil;

    if (![moc save:&error]) {
        DebugLog(@"Whoops, couldn't save:%@", [error localizedDescription]);
    }

} else {
    NSLog(@"SESSION ALREADY ADDED");
}

并将此方法添加到文件中的某个位置：

#import "YourAppDelegate.h"

- (void)saveMoc:(NSNotification *)notification {
    YourAppDelegate *appDel = (YourAppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDel.managedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}

---

我也有类似的问题，但相似并不意味着相同。我不知道这对你是否有效，但你可以试试。@macbirdie向我描述了这种方法，它对我很有效

首先，导入AppDelegate头文件：

#import "YourAppDelegate.h"

- (void)saveMoc:(NSNotification *)notification {
    YourAppDelegate *appDel = (YourAppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDel.managedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}

然后，更新您的代码：

if ([_sessionData.added isEqualToNumber:[NSNumber numberWithBool:NO]]) {

    [_sessionData setValue:[NSNumber numberWithBool:YES] forKey:@"added"];

    NSManagedObjectContext *moc = [[DataSingleton sharedMySingleton] managedObjectContext];

    SessionData *session = (SessionData*) [NSEntityDescription insertNewObjectForEntityForName:@"NewSessions" inManagedObjectContext:moc];

    session.startDate = _sessionData.startDate;
    session.endDate = _sessionData.endDate;
    session.sessionLocation = nil;
    session.sessionTitle = _sessionData.sessionTitle;
    session.sessionDescription = _sessionData.sessionDescription;
    session.added = [NSNumber numberWithBool:YES];

    _addButton =  [[[UIBarButtonItem alloc] initWithTitle:@"Remove" style:UIBarButtonSystemItemAdd target:self action:nil] autorelease];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveMoc:) name:NSManagedObjectContextDidSaveNotification object:moc];

    NSError *error = nil;

    if (![moc save:&error]) {
        DebugLog(@"Whoops, couldn't save:%@", [error localizedDescription]);
    }

} else {
    NSLog(@"SESSION ALREADY ADDED");
}

并将此方法添加到文件中的某个位置：

#import "YourAppDelegate.h"

- (void)saveMoc:(NSNotification *)notification {
    YourAppDelegate *appDel = (YourAppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDel.managedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}