Parse JSON data using Asihttprequest and the Json framework for iphone

Question

I've been learning how to parse JSON using the JSON framework and ASIHTTPRequest for iOS. I've tested using twitter feeds and also a custom feed through a community tutorial. All is going well.

I then thought I'll test using the Microsoft Odata Service for Northwind db. You can view the json results here:

http://jsonviewer.stack.hu/#http://services.odata.org/Northwind/Northwind.svc/Products%281%29?$format=json

Now I've struggling to work out how to parse just the product name. Can anyone point me in the right direction?

On my requestFinished i have this:

- (void)requestFinished:(ASIHTTPRequest *)request
{    
    [MBProgressHUD hideHUDForView:self.view animated:YES];
    NSString *responseString = [request responseString];
    NSDictionary *responseDict = [responseString JSONValue];

    //find key in dictionary
    NSArray *keys = [responseDict allKeys];

    NSString *productName = [responseDict valueForKey:@"ProductName"];
    NSLog(@"%@",productName);
}

In the log I have null.

If I change the valueforKey to @"d" I get the whole of the payload but I just want the productName.

The service URL I am using is:

http://servers.odata.org/Northwind/Northwind.svc/Products(1)?$format=json

Answer 1

According to the link you have provided, your JSON has the following format:

{
  "d": {
    ...
    "ProductName": "Chai",
    ...
  }
}

At the top level, you only have one key: "d". If you do this:

NSString *productName = [responseDict valueForKey:@"ProductName"];

It will return nil. You need to get deeper in the hierarchy:

NSDictionary *d = [responseDict valueForKey:@"d"];
NSString *productName = [d valueForKey:@"ProductName"];

Or simply:

NSString *productName = [responseDict valueForKeyPath:@"d.ProductName"];