从字典数组映射到 Swift 中的数字数组

Question

这是一个函数，它应该将包含 Dictionary<String, Any> 的订单 NSArray 的键值对数组转换为每个订单 ([NSNumber]) 的 ID 数组。

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({[=11=]["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{[=10=]["orderID"] as? Int }
}

Answer 2

这是有效的方法，将 ordersWithKeyValuePairs 转换为 [Dictionary<String, Any>] 解决了我的问题：

@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:[Dictionary<String, Any>] = userInfo["orders"] as! [Dictionary<String, Any>]
    // 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({[=10=]["orderID"] as? NSNumber}) // Line with the error

    return orderIDs
}

从字典数组映射到 Swift 中的数字数组

Mapping from array of dictionaries to array of numbers in Swift

mapping

nsarray

ios

swift

swift4