Swift Core Data - 组不起作用 [英] Swift Core Data - Group doesn't Work

问题描述

我正在开发一个简单的 iOS Swift 应用程序，但找不到任何解决核心数据小问题的方法.我必须对从核心数据中提取的一些数据进行分组，但它不起作用.

I am working on a simple iOS Swift app and can't find any solution for a small problem with core data. I have to group some data which i fetch out of core data, but it doesn't work.

这是我的 fetchRequest:

This is my fetchRequest:

<NSFetchRequest: 0x7f82fbe105e0> (entity: Sets; predicate: ((null)); sortDescriptors: ((
    "(sort, ascending, compare:)"
)); type: NSDictionaryResultType; includesPendingChanges: NO; propertiesToFetch: ((
    name
)); propertiesToGroupBy: ((
    name
)); )

我已经排序并添加了要分组的属性.还设置了一个结果类型——DictionaryResultType.

I have sort and added properties to group by. There is also set a result type - DictionaryResultType.

这是我的 FetchRequest:

And here is my FetchRequest:

fetchRequest = NSFetchRequest(entityName:entity)
fetchRequest.propertiesToGroupBy = groupDescriptors
fetchRequest.propertiesToFetch = propertiesToFetch
fetchRequest.resultType = .DictionaryResultType
let fetchedResults = managedContext.executeFetchRequest(fetchRequest as NSFetchRequest, error: &error) as? [NSManagedObject]

• 实体是一个字符串变量
• groupDescriptors 和 propertiesToFetch 是字符串数组

推荐答案

好的，我找到了一个解决方案，而且很简单.

Ok I found a solution and it's just simple.

managedContext.executeFetchRequest(fetchRequest as NSFetchRequest, error: &error) as? [NSManagedObject]

只生成 NSManagedObject 的.如果您将获取请求更改为

generates only NSManagedObject's. If you change the fetch request to

managedContext.executeRequest(fetchRequest, withContext: managedContext as! NSManagedObjectContext, error: nil) as! [AnyObject]

您将收到您的数据.

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