Hasan Nizamani Hasan Nizamani - 1 year ago 86
Swift Question

Simple and clean way to convert JSON string to Object in Swift

I have been searching for days to convert a fairly simple JSON string to an object type in Swift but with no avail.

Here is the code for web service call:

func GetAllBusiness() {

Alamofire.request(.GET, "http://MyWebService/").responseString { (request, response, string, error) in

println(string)

}
}


I have a swift struct Business.swift:

struct Business {
var Id : Int = 0
var Name = ""
var Latitude = ""
var Longitude = ""
var Address = ""
}


Here is my test service deployed:

[
{
"Id": 1,
"Name": "A",
"Latitude": "-35.243256",
"Longitude": "149.110701",
"Address": null
},
{
"Id": 2,
"Name": "B",
"Latitude": "-35.240592",
"Longitude": "149.104843",
"Address": null
}
...
]


It would be a delight if someone guide me through this.

Thanks.

Answer Source

Here are some tips how to begin with simple example.

Consider you have following JSON Array String (similar to yours) like:

 var list:Array<Business> = []

  // left only 2 fields for demo
  struct Business {
    var id : Int = 0
    var name = ""               
 }

 var jsonStringAsArray = "[\n" +
        "{\n" +
        "\"id\":72,\n" +
        "\"name\":\"Batata Cremosa\",\n" +            
        "},\n" +
        "{\n" +
        "\"id\":183,\n" +
        "\"name\":\"Caldeirada de Peixes\",\n" +            
        "},\n" +
        "{\n" +
        "\"id\":76,\n" +
        "\"name\":\"Batata com Cebola e Ervas\",\n" +            
        "},\n" +
        "{\n" +
        "\"id\":56,\n" +
        "\"name\":\"Arroz de forma\",\n" +            
    "}]"


        // convert String to NSData
        var data: NSData = jsonStringAsArray.dataUsingEncoding(NSUTF8StringEncoding)!
        var error: NSError?

        // convert NSData to 'AnyObject'
        let anyObj: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions(0),
            error: &error)
        println("Error: \(error)")

     // convert 'AnyObject' to Array<Business>
     list = self.parseJson(anyObj!)

     //===============

    func parseJson(anyObj:AnyObject) -> Array<Business>{

        var list:Array<Business> = []

         if  anyObj is Array<AnyObject> {

            var b:Business = Business()

            for json in anyObj as Array<AnyObject>{
             b.name = (json["name"] as AnyObject? as? String) ?? "" // to get rid of null
             b.id  =  (json["id"]  as AnyObject? as? Int) ?? 0                 

               list.append(b)
            }// for

        } // if

      return list

    }//func    

[EDIT]

To get rid of null changed to:

b.name = (json["name"] as AnyObject? as? String) ?? ""
b.id  =  (json["id"]  as AnyObject? as? Int) ?? 0 

See also Reference of Coalescing Operator (aka ??)

Hope it will help you to sort things out,