无法将类型'__NSCFSet'（0x109b56408）的值强制转换为'NSArray'Swift 4

Question

我正在尝试从notification.userInfo插入和删除的值中获取位置对象的数组，并相应地更新地图注释。它不允许我将其强制转换为类型[Location]。

我收到以下错误

  

无法将类型'__NSCFSet'（0x109b56408）的值强制转换为'NSArray'

var managedObjectContext: NSManagedObjectContext! {
    didSet {
        NotificationCenter.default.addObserver(forName: Notification.Name.NSManagedObjectContextObjectsDidChange, object: managedObjectContext, queue: OperationQueue.main) { (notification) in
            if self.isViewLoaded {
                if let dictionary = notification.userInfo {
                    print(dictionary["inserted"])

                    if let inserted = dictionary["inserted"]{
                        var location = [Location]()
                        location = inserted as! [Location]
                    }

                    if let deleted = dictionary["deleted"] {
                    }
                }
            }
        }
    }
}

Answer 1

数据不是数组，而是集合。并使用适当的键来访问数据。

var managedObjectContext: NSManagedObjectContext! {
    didSet {
        NotificationCenter.default.addObserver(forName: Notification.Name.NSManagedObjectContextObjectsDidChange, object: managedObjectContext, queue: OperationQueue.main) { (notification) in
            if self.isViewLoaded {
                if let dictionary = notification.userInfo {
                    print(dictionary[NSInsertedObjectsKey])

                    if let inserted = dictionary[NSInsertedObjectsKey] as? Set<Location> {
                        var location = Array(inserted)
                    }

                    if let deleted = dictionary[NSDeletedObjectsKey] {
                    }
                }
            }
        }
    }
}