Swift 3 / XCode 8 NSManagedObjectContext.fetch错误 [英] Swift 3/XCode 8 NSManagedObjectContext.fetch error

问题描述

我正在迁移到Swift 3，并在迁移抽象CoreData查询代码时遇到一个非常奇怪的错误消息。 entityName 传递给以下方法：

I am migrating to Swift 3 and have come across a very strange error message while migrating abstract CoreData query code. entityName is passed to the following method:

func objects(entityName name:String)->[NSManagedObject]? {   
  let fetchRequest: NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName:name)
  var objects: [NSManagedObject]?
  do {
    objects = try managedObjectContext.fetch(fetchRequest)
  } catch { ... }
}

这会导致以下错误：

无法使用参数列表类型（NSFetchRequest< NSFetchRequestResult>）'
期望的类型为'（NSFetchRequest< NSFetchRequestResult>）'的参数列表

Cannot invoke 'fetch' with an argument list of type '(NSFetchRequest<NSFetchRequestResult>)' Expected an argument list of type '(NSFetchRequest<NSFetchRequestResult>)'

错误是说我不能使用其期望的类型。
是否可以像这样在Swift 3中对CoreData进行抽象调用？

The error is stating I can't use the type its expecting. Is it possible to make abstract calls to CoreData like this in Swift 3?

帖子 Swift 3，NSFetchrequest 是

我尝试了 fetchRequest ，但它没有改变任何东西。
managedObjectContext.fetch（fetchRequest as！NSFetchRequest< NSFetchRequestResult>）

I tried to cast fetchRequest, but it didn't change anything. managedObjectContext.fetch(fetchRequest as! NSFetchRequest<NSFetchRequestResult>)

推荐答案

尝试：

do {
    objects = try managedObjectContext.fetch(fetchRequest) as! [YourEntityName]
  } catch {
  print(error)
}

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