How to parse JSON in Objective-C

Question

i have this json string

{
    "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/",
    "city": [
        {
            "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ABJ/",
            "agencyCollection": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ABJ/agencyCollection/"
            },
            "codecit": "ABJ",
            "country": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ABJ/country/"
            },
            "namecit": "ABIDJAN"
        },
        {
            "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/",
            "agencyCollection": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/agencyCollection/",
                "agency": [
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/agencyCollection/3/"
                    },
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/agencyCollection/4/"
                    }
                ]
            },
            "codecit": "ALG",
            "country": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/country/"
            },
            "namecit": "ALGER"
        },
        {
            "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/",
            "agencyCollection": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/agencyCollection/",
                "agency": [
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/agencyCollection/5/"
                    },
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/agencyCollection/6/"
                    }
                ]
            },
            "codecit": "AMS",
            "country": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/country/"
            },
            "namecit": "AMSTERDAM"
        }
    ]
}

I want to parse it, I wrote this code

NSString *myJSON = [[NSString alloc] initWithContentsOfFile:responseString encoding:NSUTF8StringEncoding error:NULL];   
NSDictionary *json    = [myJSON JSONValue];
//NSLog(responseString);
NSArray *citysList    =  [json objectForKey:@"city"];
NSLog(@"ok");
NSLog(@" number of element : %@", [citysList count]);

But I have 0 number of element , help please

CharlieMezak · Accepted Answer · 2011-05-24 00:34:29Z

1

Michael is right. Here's a more detailed answer:

initWithContentsOfFile takes a string containing a file path (e.g. "/users/mehdi/documents/myFile.txt"). You seem to be passing in your actual JSON string, which isn't a file path. As a result, initWithContentsOfFile is probably returning nil.

Check this by asking:

if (myJSON == nil) NSLog(@"myJSON variable == nil!");

If it is nil, then your code is also setting json and citysList to nil.

Try this:

NSDictionary *json    = [responseString JSONValue];
NSArray *citysList    =  [json objectForKey:@"city"];
NSLog(@" number of element : %d", [citysList count]);

answered May 24, 2011 at 0:34

CharlieMezak

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Comments

Michael Petrov · Accepted Answer · 2011-05-23 23:13:19Z

1

You're doing an initWithContentsOfFile but passing in a string. Have you tried simply [responseString JSONValue]? Your code suggests that responseString has the PATH to the file you're trying to open, not your full response string itself.

answered May 23, 2011 at 23:13

Michael Petrov

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