Question

我正在使用Xcode版本8.0 beta 6.我正在尝试声明获取结果控制器，但它一直显示错误 “引用泛型类型”NSFetchedResultsController“需要＆lt; ...＆gt;

中的参数

   var fetchedResultsController : NSFetchedResultsController!

Xcode建议我使用

修复它

var fetchedResultsController : NSFetchedResultsController<AnyObject>!

也会抛出错误“Type'AnyObject'不符合协议'NSFetchRequestResult'

Answer 1

这里是我通常如何宣布我的：

lazy var fetchedResultsController: NSFetchedResultsController = {
    let fetchRequest = NSFetchRequest(entityName: "Friend")
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: "lastMessage.timestamp", ascending: false)]
    let predicate = NSPredicate(format: "lastMessage.timestamp != nil")
    fetchRequest.predicate = predicate
    let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
    let frc = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
    frc.delegate = self
    return frc

}()

为什么我不能声明NSFetchResultsController？

1 个答案: