Iterate through NSDictionary and save it into an array of object type

问题

As the title states, I would like to iterate through a NSDictionary and save the single entries into an array of object type. I am currently struggling to read out the single entries of the NSDictionary, as I cannot simply call them with entry[index] and count upwards.

I've got a local JSON file named "Clients", which I get into swift. The file looks like this:

{
    "clients": [
        {
            "id": 3895,
            "phone": 0787623,
            "age" : 23,
            "customerSince" : 2008
        },
        {
             "id": 9843,
            "phone": 7263549,
            "age" : 39,
            "customerSince" : 2000
        },
         {
             "id": 0994,
            "phone": 1093609,
            "age" : 42,
            "customerSince" : 1997
        }
    ]
}

What did I do? I created a class ClientObjects, which looks like this:

import Foundation

class ClientObjects{

    var id : Int = 0;
    var phone : Int = 0;
    var age : Int = 0;
    var customerSince : Int = 0;      
}

Next I realized the JSON import into Swift, which works properly. When I debug the session, the jsonResult variable contains the data of the JSON. But somehow I couldn't manage to process the data into the array of the object type ClientObjects.

   // instantiate the ClientObjects as an Array
        var clientsArray = [ClientObjects]();

        func getData() {

            if let path = NSBundle.mainBundle().pathForResource("Clients", ofType: "json")
            {
                if let jsonData = NSData(contentsOfFile:path)
                {   
                   do {
                        if let jsonResult = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableLeaves) as? NSDictionary
                        {
                            //print(jsonResult["clients"]);
                            // this print call returns the whole content of the JSON array

                           if let clients = jsonResult["clients"] as? [[String: AnyObject]] {
                                for client in clients {

                                   clientsArray.append(client);

                    }
                    catch let error as NSError {
                            print("API error: \(error.debugDescription)")
                    }
                    }
                }

            }
}

The goal is, that I can print out single attributes of clients, like:

clientsArray[0].id;

Can somebody please give me some advice on my issue?

回答1:

First of all let's take a look at ClientObject.

It should be a struct
It should be simply named Client
The properties should be constants without a default value
It should have a failable initializer
The phone should be a String (please change your JSON accordingly)

Like this

struct Client {
    let id: Int
    let phone: String
    let age: Int
    let customerSince: Int

    init?(json:[String:Any]) {
        guard let
            id = json["id"] as? Int,
            phone = json["phone"] as? String,
            age = json["age"] as? Int,
            customerSince = json["customerSince"] as? Int else { return nil }
        self.id = id
        self.phone = phone
        self.age = age
        self.customerSince = customerSince
    }
}

Now let's read the JSON

func getData() {
    do {
        guard let
            path = NSBundle.mainBundle().pathForResource("Clients", ofType: "json"),
            jsonData = NSData(contentsOfFile:path),
            jsonResult = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableLeaves) as? NSDictionary,
            jsonClients = jsonResult["clients"] as? [[String: Any]] else { return }

        let clients = jsonClients.flatMap(Client.init) // <- now you have your array of Client

    } catch let error as NSError {
        print("API error: \(error.debugDescription)")
    }
}

回答2:

You have to create ClientObjects objects and assign the values to the appropriate properties.

...
let jsonResult = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as! [String:AnyObject]
if let clients = jsonResult["clients"] as? [[String: Int]] {
  for client in clients {
    let newClient = ClientObjects()
    newClient.id = client["id"]!
    newClient.phone = client["phone"]!
    newClient.age = client["age"]!
    newClient.customerSince = client["customerSince"]!
    clientsArray.append(newClient);
  }
}
...

It's recommended to name classes with singular forms in this case ClientObject

And no if - let nor Foundation types like NSDictionary nor MutableLeaves options in the NSJSONSerialization line.

来源：https://stackoverflow.com/questions/35564194/iterate-through-nsdictionary-and-save-it-into-an-array-of-object-type

标签

ios

arrays

json

swift

nsdictionary