ios - AnyObject 快速数组

Question

给出以下函数:

class func collection(#response: NSHTTPURLResponse,
                       representation: AnyObject) -> [City] {
    return []
}

所以这个函数应该返回一个城市对象数组。我必须以某种方式将 AnyObject 类型的表示变量转换为城市数组。

我不知 Prop 体的表示类型是什么，但我可以做类似的事情

println(representation[0])

它将打印该对象。有什么想法如何将表示形式转换为 [City] 数组吗？

更新

正在做

println(representation as [City]) 

打印 nil。

City.swift:

final class City : ResponseCollectionSerializable {

    let id: String
    let name: String

    class func collection(#response: NSHTTPURLResponse, representation: AnyObject) -> [City] {
        return []
    }
}

这只是从 https://github.com/Alamofire/Alamofire#generic-response-object-serialization 复制并粘贴的它应该将 JSON 响应序列化为对象:

@objc public protocol ResponseCollectionSerializable {
    class func collection(#response: NSHTTPURLResponse, representation: AnyObject) -> [Self]
}

extension Alamofire.Request {

    public func responseCollection<T: ResponseCollectionSerializable>(completionHandler: (NSURLRequest, NSHTTPURLResponse?, [T]?, NSError?) -> Void) -> Self {
        let serializer: Serializer = { (request, response, data) in
            let JSONSerializer = Request.JSONResponseSerializer(options: .AllowFragments)
            let (JSON: AnyObject?, serializationError) = JSONSerializer(request, response, data)
            if response != nil && JSON != nil {
                return (T.collection(response: response!, representation: JSON!), nil)
            } else {
                return (nil, serializationError)
            }
        }

        return response(serializer: serializer, completionHandler: { (request, response, object, error) in
            completionHandler(request, response, object as? [T], error)
        })
    }
}

Answer 1

您返回的 representation 参数是调用 NSJSONSerialization.JSONObjectWithData... 的结果，因此它是一个 NSArray 或 NSDictionary。由于您获得了 representation[0] 的值，我们知道它是一个 NSArray。您的代码到底是什么样子取决于 JSON(您应该在这样的问题中包含一个示例)，但您的代码需要类似于(前面未经测试的代码):

class func collection(#response: NSHTTPURLResponse, representation: AnyObject) -> [City] {
    var cities: [City] = []
    for cityRep in representation {
        // these next two lines should grab the city data using the correct key
        let id = cityRep.valueForKey("cityID") as String
        let name = cityRep.valueForKey("cityName") as String
        // now add the city to our list
        cities.append(City(id: id, name: name))
    } 
    return cities
}