本文介绍了如何在iOS 10 Swift 3中初始化NSFetchedResultsController的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我无法使用Swift 3在iOS 10中初始化NSFetchedResultsController。
I can't get my NSFetchedResultsController initialized in iOS 10 using Swift 3.
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的通用类型，但它不会正确推断实体类型。我已明确尝试：
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)
也不幸。
谢谢！
推荐答案
NSFetchRequest 现在是通用的。 NSFetchedResultsController 是一个通用的。因此，在声明变量时，必须使用一个通用声明，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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