如何在 iOS 10 Swift 3 中初始化 NSFetchedResultsController [英] How to initialize a NSFetchedResultsController in iOS 10 Swift 3

问题描述

我无法在 iOS 10 中使用来自 NSFetchedResultsController>AECoreDataUI.

I can't get my NSFetchedResultsController initialized in iOS 10 using Swift 3 within CoreDataTableViewController from AECoreDataUI.

let request = NSFetchRequest<NasaPicture>(entityName:"NasaPicture")  
request.predicate = Predicate(format: "isPagedResult == YES")  
request.sortDescriptors = [SortDescriptor(key: "date", ascending: false)]  
fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: moc, sectionNameKeyPath: nil, cacheName: nil)  

编译器抱怨

"Cannot convert value of type NSFetchedResultsController<NasaPicture> to expected type NSFetchedResultsController<_>"

控制器现在使用 swift 的泛型类型，但它没有正确推断实体类型.我已经明确尝试过:

The controller is now using generic type for swift, but it is not inferring the entity type correctly. I've tried explicitly:

fetchedResultsController = NSFetchedResultsController<NasaPicture>(fetchRequest: request, managedObjectContext: moc, sectionNameKeyPath: nil, cacheName: nil)  

也不走运.

谢谢！

推荐答案

NSFetchRequest 现在是通用的.NSFetchedResultsController 也是一个泛型.因此，在声明变量时，必须使用泛型声明，例如:

NSFetchRequest is now a generic. NSFetchedResultsController is a generic too. Therefore, when declaring variables, you have to use a generic declaration, e.g.:

var fetchedResultsController: NSFetchedResultsController<NasaPicture>?

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