使用Swift 2.1遍历字典的JSON命名数组

Question

I'm pulling a JSON array of dictionaries trying to add them to a class I created and use them for a UITableView . The JSON would look like this:

   {  
       "inventory":[  
          {  
             "item":"item 1",
             "description":"item 1 description",
             "quantityOnHand":"42",
             "supplier_id":"1",
             "supplierName":"Supplier 1"
          },
          {  
             "item":"item 2",
             "description":"item 2 description",
             "quantityOnHand":"1001",
             "supplier_id":"1",
             "supplierName":"Supplier 1"
          } ...

and so on...

I'm grabbing all this in my viewDidLoad() and trying to add each dictionary to a class (called Inventory ) to work with later. Here's where I'm serializing my JSON:

override func viewDidLoad() {
    super.viewDidLoad()

    let urlString = "my url to json data";
    let session = NSURLSession.sharedSession();
    let url = NSURL(string: urlString)!;

    session.dataTaskWithURL(url) { (data: NSData?, response:NSURLResponse?, error: NSError?) -> Void in
        if let responseData = data {
            do {
                let json = try NSJSONSerialization.JSONObjectWithData(responseData, options: NSJSONReadingOptions.AllowFragments)

                print(json) //this prints out the above formatted json



                 if let dict = json as? Dictionary<String, AnyObject> {
                        print(dict["inventory"]![0]!["description"]);
                        print(dict["inventory"]![0]!["item"]);
                        print(dict["inventory"]![0]!["quantityOnHand"]);
                 }
            } catch {
                print("Could not serialize");
            }
       }
    }.resume()
}

I'm able to print out each value using something like print(dict["inventory"]![0]!["description"]); but that seems inefficient.

Do I need a for loop counting the number of dictionaries? Or a for (key, value) loop? The fact that it's a bunch of dictionaries inside of an array named inventory is really throwing me off. If it were JSON returning key:value pairs in a single dictionary I think I could figure it out on my own. I'm sort of stuck on what to do after putting my json["inventory"] into a variable.

Answer 1

First of all cast the JSON serialization to something meaningful,
in this case Dictionary<String, AnyObject>

let json = try NSJSONSerialization.JSONObjectWithData(responseData, options: NSJSONReadingOptions.AllowFragments) as! Dictionary<String, AnyObject>

Then retrieve the array of dictionaries, the JSON string reveals that it contains only String types.

let inventoryArray = dict["inventory"] as! [Dictionary<String, String>]

if inventory is optional, use optional bindings

if let inventoryArray = dict["inventory"] as? [Dictionary<String, String>] { }

Now you can get the items in the array with a simple loop, any type casting is not needed.

for anItem in inventoryArray {
   print("description:", anItem["description"])
   print("item: ", anItem["item"])
   print("quantityOnHand: ", anItem["quantityOnHand"])
}