Importing JSON objects into NSArray

Question

Trying to parse this JSON object in objective-C and creating an NSArray with these objects. The first value is a counter and is specific for the object. All other values are unique.

{ "myData": [
["1","1","110","dollar","8.0","2.8","0.1","11.6"],
["2","1","110","euro","4.0","3.2","1.5","4.4"],
["3","1","120","rupier","6.0","2.9","1.3","10.8"],
["4","1","120","dinero","4.0","3.3","1.5","4.4"],
["5","2","130","drahmer","8.0","2.9","1.3","11.2"],
] }

Tried this code:

 NSDictionary* json = [NSJSONSerialization 
                          JSONObjectWithData:myData
                          options:kNilOptions 
                          error:&error];

    NSArray *currencyInformation = [json objectForKey:@"myData"];

But the objects are not there. Though the count of the array is 5.

if [array count] is 5 as expected, the objects are there. How do you know they aren't? — user529758
– user529758, Commented Mar 18, 2012 at 20:59
Can´t read them from the array. Since they don't have any description for the value, ie. "currency": "dollar" I can't ready them out... — linge
– linge, Commented Mar 18, 2012 at 21:04
Where is currency? I don't see that in the JSON at all. Show us how you're accessing the values in the array. (Hint: they will be NSArrays themselves). — mattjgalloway
– mattjgalloway, Commented Mar 18, 2012 at 21:20
@mattjgalloway: There you got it. Every line is an array in it self. When handling it like an array it solved the problem. Thanks. — linge
– linge, Commented Mar 18, 2012 at 21:30
@linge - Well I've added an answer to say that :-). Glad it helped. — mattjgalloway
– mattjgalloway, Commented Mar 18, 2012 at 21:33

mattjgalloway · Accepted Answer · 2012-03-18 21:32:54Z

2

Each object in the array is an array itself, so:

NSDictionary* json = [NSJSONSerialization 
                      JSONObjectWithData:myData
                      options:kNilOptions 
                      error:&error];

NSArray *currencyInformation = [json objectForKey:@"myData"];

for (NSArray *info in currencyInformation) {
    // Then access each "column" with [info objectAtIndex:0,1,2,3,...]
}

answered Mar 18, 2012 at 21:32

mattjgalloway

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Paul.s · Accepted Answer · 2012-03-18 21:32:54Z

1

In this data structure you would need to access things by index e.g

for (NSArray *currency in currencyInformation) {
    NSLog(@"Currency: %@", [currency objectAtIndex:3]);
}

If you want to access things by key then you would need to change your JSON to use an array of objects instead of an array of arrays. Something like this:

{ 
    "myData": [
        {
            "primaryKey" : 1,
            "currency"   : "dollar",
            <other keys + values>...
        },
    ]
}

In which case you could now do something like:

for (NSDictionary *currency in currencyInformation) {
    NSLog(@"Currency: %@", [currency valueForKey:@"currency"]);
}

edited Mar 18, 2012 at 21:32

answered Mar 18, 2012 at 21:27

Paul.s

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