您知道有什么方法可以删除存储在Core Data中的所有条目吗?我的schema应该保持不变;我只想把它重置为空白。


Edit

我希望以编程方式做到这一点,这样用户就可以基本上按下重置按钮。


当前回答

你可以删除SQLite文件-但我选择通过一个函数单独清除表来做到这一点:

- (void) deleteAllObjects: (NSString *) entityDescription  {
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:entityDescription inManagedObjectContext:_managedObjectContext];
    [fetchRequest setEntity:entity];

    NSError *error;
    NSArray *items = [_managedObjectContext executeFetchRequest:fetchRequest error:&error];
    [fetchRequest release];


    for (NSManagedObject *managedObject in items) {
        [_managedObjectContext deleteObject:managedObject];
        DLog(@"%@ object deleted",entityDescription);
    }
    if (![_managedObjectContext save:&error]) {
        DLog(@"Error deleting %@ - error:%@",entityDescription,error);
    }

}

我选择逐表执行的原因是,它使我在编程时确认删除表的内容是合理的,并且没有我宁愿保留的数据。

这样做会比仅仅删除文件慢得多,如果我这个方法花费太长时间,我将更改为文件删除。

其他回答

你们都把事情搞复杂了。你可以发送你的NSManagedObjectContext重置方法

iOS 10 + Swift 3解决方案:

func clearCoreDataStore() {
    let delegate = UIApplication.shared.delegate as! AppDelegate
    let context = delegate.persistentContainer.viewContext

    for i in 0...delegate.persistentContainer.managedObjectModel.entities.count-1 {
        let entity = delegate.persistentContainer.managedObjectModel.entities[i]

        do {
            let query = NSFetchRequest<NSFetchRequestResult>(entityName: entity.name!)
            let deleterequest = NSBatchDeleteRequest(fetchRequest: query)
            try context.execute(deleterequest)
            try context.save()

        } catch let error as NSError {
            print("Error: \(error.localizedDescription)")
            abort()
        }
    }
}

遍历所有核心数据实体并清除它们

这里是清洗核心数据的组合解决方案。

- (void)deleteAllObjectsInCoreData
{
    NSArray *allEntities = self.managedObjectModel.entities;
    for (NSEntityDescription *entityDescription in allEntities)
    {
        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
        [fetchRequest setEntity:entityDescription];

        fetchRequest.includesPropertyValues = NO;
        fetchRequest.includesSubentities = NO;

        NSError *error;
        NSArray *items = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];

        if (error) {
                NSLog(@"Error requesting items from Core Data: %@", [error localizedDescription]);
            }

        for (NSManagedObject *managedObject in items) {
            [self.managedObjectContext deleteObject:managedObject];
        }

        if (![self.managedObjectContext save:&error]) {
            NSLog(@"Error deleting %@ - error:%@", entityDescription, [error localizedDescription]);
        }
    }  
}

龙道9+ Swift 2

删除所有实体中的所有对象

func clearCoreDataStore() {
    let entities = managedObjectModel.entities
    for entity in entities {
        let fetchRequest = NSFetchRequest(entityName: entity.name!)
        let deleteReqest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
        do {
            try context.executeRequest(deleteReqest)
        } catch {
            print(error)
        }
    }
}

删除持久存储文件并设置一个新的持久存储协调器?