删除持久存储文件并设置一个新的持久存储协调器?

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]);
        }
    }  
}

删除持久存储文件并设置一个新的持久存储协调器?

下面这个版本可以删除每个表中的每条记录。

斯威夫特4

static func resetDatabase() {
    do {
        try dataStore.persistentStoreCoordinator.managedObjectModel.entities.forEach { (entity) in
            if let name = entity.name {
                let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: name)
                let request = NSBatchDeleteRequest(fetchRequest: fetch)
                try mainContext.execute(request)
            }
        }

        try mainContext.save()
    } catch {
        print("error resenting the database: \(error.localizedDescription)")
    }
}

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。

迅速的解决方案:

class func deleteAllManagedObjects() {

        let modelURL = NSBundle.mainBundle().URLForResource("some string", withExtension: "mom")
        let mom = NSManagedObjectModel(contentsOfURL: modelURL)

        for entityName in mom.entitiesByName.keys {
            let fr = NSFetchRequest(entityName: entityName as String)
            let a = Utility.managedObjectContext().executeFetchRequest(fr, error: nil) as [NSManagedObject]
            for mo in a {
                Utility.managedObjectContext().deleteObject(mo)
            }
        }

        Utility.managedObjectContext().save(nil)
    }