向下[AnyObject]到[String]和[PFObject]

Question

我有一个[AnyObject]数组，并希望将其转换为[PFObject]和[String]。这样做的正确方法是什么？我被告知as String不是从AnyObject转发的理想方式。

目前使用此代码将数组中的对象转换为String：

    restaurantNames = finalRestaurantArray.map { $0.objectForKey("Name") as String }

数组如下所示：

[<Restaurant: 0x7feb9252cfc0, objectId: LA74J92QDA, localId: (null)> {
    Name = "Restaurant 1";        
    City = "New York";
    Closed = 1;
    Country = "United States";
    FoodType = Japanese;
}, <Restaurant: 0x7feb926afa00, objectId: 0aKFrpKN46, localId: (null)> {
    Name = "Restaurant 2";        
    City = "San Francisco";
    Closed = 1;
    Country = "United States";
    FoodType = Italian;
}]

Answer 1

您可以使用以下内容：

let restaurantNames = finalRestaurantArray.map {
  $0["Name"] as? String ?? ""
}

如果向下转发失败，??会设置默认值。