ios - 从字典数组映射到 Swift 中的数字数组

Question

这是一个函数，它应该为订单 NSArray 转换一个键值对数组包含 Dictionary<String, Any>到每个订单的 ID 数组 ( [NSNumber] )。

但是，我还是遇到了类型转换的问题，错误:

Type 'Any' has no subscript members

如何在 Swift 中干净地执行映射？

@objc static func ordersLoaded(notification:Notification) -> [NSNumber] {   

    // Function receives a Notification object from Objective C     
    let userInfo:Dictionary = notification.userInfo as! Dictionary<String, Any>

    // orders is an array of key-value pairs for each order Dictionary<String,Any>
    let ordersWithKeyValuePairs:NSArray = userInfo["orders"] as! NSArray // Here a typed array of Dictionaries would be preferred

    // it needs to be simplified to an array of IDs for each order (NSNumber)
    // orderID is one of the keys
    let orderIDs:[NSNumber];
    orderIDs = ordersWithKeyValuePairs.flatMap({$0["orderID"] as? NSNumber}) // Line with the error
    /*
    orderIDs = ordersWithKeyValuePairs.map({
        (key,value) in
        if key==["orderID"] {
            return value
        } else {
            return nil
        }
    }) as! [NSNumber]
    */

    return orderIDs
}

Answer 1

你可以试试这个

if let ordersWithKeyValuePairs = userInfo["orders"] as? [[String:Any]] {

   let result = ordersWithKeyValuePairs.compactMap{$0["orderID"] as? Int }
}