AnyObject to array in swift - ios

Question

Following function is given:
class func collection(#response: NSHTTPURLResponse,
representation: AnyObject) -> [City] {
return []
}
So this function should return an array of city objects. I have to somehow transform the representation variable that is of type AnyObject to a city array.
I don't know what the exact type of representation is but I can do things like
println(representation[0])
and it will print the object. Any ideas how to transform representation to [City] array?
Update
Doing
println(representation as [City])
prints nil.
City.swift:
final class City : ResponseCollectionSerializable {
let id: String
let name: String
class func collection(#response: NSHTTPURLResponse, representation: AnyObject) -> [City] {
return []
}
}
This is just copy and pasted from https://github.com/Alamofire/Alamofire#generic-response-object-serialization It should serialize a JSON response into objects:
#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

The representation parameter you're getting back is the result of a call to NSJSONSerialization.JSONObjectWithData..., so it's either a NSArray or a NSDictionary. Since you get a value for representation[0], we know it's an NSArray. Exactly what your code looks like will depend on the JSON (a sample of which you should include in a question like this), but your code will need to be something like (untested code ahead):
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
}

Answer 2

Assuming (and although I hate to make assumptions, your question is a bit vague about the details) that the representation is either an NSData object that represents the response, or an Array that you have created from the response.
In my experience, such a response is an array of dictionaries that you can use to create city objects. So you need to write a function that transforms this dictionary into a City object. Something with the signature:
parser (AnyObject) -> City
Now, you could just iterate through the array, apply this function to each dictionary, collect the results into an Array and return the result.
But you could be classier and map your function over the array and return the result.