Question

我在表视图控制器中使用了一个lazy var来从CoreData获取数据。它在swift2中运行良好。但是当我升级到Swift3时，它显示如下错误。请帮我改变Swift3

错误：无法转换类型＆＃39;错误＆＃39;的值指定类型＆＃39; NSFetchedResultsController＆＃39;

lazy var fetchedResultsController: NSfetchedResultsController =
{
    let fetchRequest = NSFetchRequest(entityName: "EvtIvtTbl")
    let sortDescriptor = NSSortDescriptor(key: "bym_kol", ascending: true)
    fetchRequest.sortDescriptors = [sortDescriptor]

    let fetchedResultsController = NSfetchedResultsController(fetchRequest: fetchRequest,
                                                     managedObjectContext: self.managedObjectContext,
                                                     sectionNameKeyPath: nil,
                                                     cacheName: nil)
    fetchedResultsController.delegate = self
    return fetchedResultsController
}()

Answer 1

在Swift 3.0中，NSFetchedResultsController和NSFetchRequest需要类型参数。假设EvtIvtTbl是您的NSManagedObject子类，您的代码应该如下所示：

lazy var fetchedResultsController: NSFetchedResultsController<EvtIvtTbl> = {
    let fetchRequest = NSFetchRequest<EvtIvtTbl>(entityName: "EvtIvtTbl")
    let sortDescriptor = NSSortDescriptor(key: "bym_kol", ascending: true)
    fetchRequest.sortDescriptors = [sortDescriptor]

    let fetchedResultsController = NSFetchedResultsController<EvtIvtTbl>(fetchRequest: fetchRequest,
                                                 managedObjectContext: self.managedObjectContext,
                                                 sectionNameKeyPath: nil,
                                                 cacheName: nil)
    fetchedResultsController.delegate = self
    return fetchedResultsController
}()

Ios Swift3：lazy var fetchrequestcontroller显示错误

1 个答案: