为什么我不能使用AlamoFire和SwiftyJson快速创建班级对象？

Question

I have a function that creates an object from json node in swift:

class func fromJSON(json: JSON) -> SingleRequest? {
    var title: String
    if let titleOrNil = json["title"].string {
        title = titleOrNil
    } else {
        title = ""
    }
    let locationName = json["location"].string
    let discipline = json["discipline"].string



     let lat = json["location"]["coordinates"][1].doubleValue
    let lon = json["location"]["coordinates"][0].doubleValue
    let coordinate = CLLocationCoordinate2D(latitude: lat, longitude: lon)
    return SingleRequest(title: title, locationName: locationName!, discipline: discipline!, coordinate: coordinate)
}

now, using alamofire and swiftyJson I'm trying to fetch all data from my webservice and create SingleRequest objects. I do it as shown below:

func fetchRequests(radius: Double, lat: Double, lon: Double){
    Alamofire.request(.GET, "https://mywebservice")
        .responseJSON { response in

            switch response.result {
            case .Success:


                if let jsonData = response.result.value {
                    for requestJSON in jsonData {
                        if let request = SingleRequest.fromJSON(requestJSON){
                           //do sth with a single request here
                           //e.g. print(request.discipline)
                        }
                    }
                }


            case .Failure(let error):
                print("SWITCH ERROR")
                print(error)
            }

    }
}

but I'm getting an error:

So my question is - how, using alamoFire and SwiftyJson I can create my custom SingleRequest ?

Answer 1

Your problem is here:

if let jsonData = response.result.value {
    for requestJSON in jsonData {
        if let request = SingleRequest.fromJSON(JSON(requestJSON)){
            //do sth with a single request here
            //e.g. print(request.discipline)
        }
    }
}

jsonData is an AnyObject that you need to cast to [[String: AnyObject]] :

if let jsonData = response.result.value as? [[String: AnyObject]] {
    for requestJSON in jsonData {
        if let request = SingleRequest.fromJSON(requestJSON){
            //do sth with a single request here
            //e.g. print(request.discipline)
        }
    }
}

What the error is saying is that since response.result.value is an AnyObject by default, it is not iterable. That's why you need to cast it to an array (eg an array of dictionaries: [[String: AnyObject]] ).

Answer 2

Admittedly, I don't know what "type" response.result.value is, but if it can be cast to something that can be iterated then here's an example of that:

if let jsonData = response.result.value as? [(some type that can be iterated)] {
    // do something with jsonData ...
}