How to use NSJSONSerialization

Question

I have a JSON string (from PHP's json_encode() that looks like this:

[{"id": "1", "name":"Aaa"}, {"id": "2", "name":"Bbb"}]

I want to parse this into some sort of data structure for my iPhone app. I guess the best thing for me would be to have an array of dictionaries, so the 0th element in the array is a dictionary with keys "id" => "1" and "name" => "Aaa".

I do not understand how the NSJSONSerialization stores the data though. Here is my code so far:

NSError *e = nil;
NSDictionary *JSON = [NSJSONSerialization 
    JSONObjectWithData: data 
    options: NSJSONReadingMutableContainers 
    error: &e];

This is just something I saw as an example on another website. I have been trying to get a read on the JSON object by printing out the number of elements and things like that, but I am always getting EXC_BAD_ACCESS.

How do I use NSJSONSerialization to parse the JSON above, and turn it into the data structure I mentioned?

Answer 1

Your root json object is not a dictionary but an array:

[{"id": "1", "name":"Aaa"}, {"id": "2", "name":"Bbb"}]

This might give you a clear picture of how to handle it:

NSError *e = nil;
NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutableContainers error: &e];

if (!jsonArray) {
  NSLog(@"Error parsing JSON: %@", e);
} else {
   for(NSDictionary *item in jsonArray) {
      NSLog(@"Item: %@", item);
   }
}

Answer 2

This is my code for checking if the received json is an array or dictionary:

NSError *jsonError = nil;
id jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:&jsonError];

if ([jsonObject isKindOfClass:[NSArray class]]) {
    NSLog(@"its an array!");
    NSArray *jsonArray = (NSArray *)jsonObject;
    NSLog(@"jsonArray - %@",jsonArray);
}
else {
    NSLog(@"its probably a dictionary");
    NSDictionary *jsonDictionary = (NSDictionary *)jsonObject;
    NSLog(@"jsonDictionary - %@",jsonDictionary);
}

I have tried this for options:kNilOptions and NSJSONReadingMutableContainers and works correctly for both.

Obviously, the actual code cannot be this way where I create the NSArray or NSDictionary pointer within the if-else block.