JSON Arrays and Sorting

Question

I have this json array which I have outlined below. I want to know how I could get all the strings under the "name" key only and place in a certain array to be sorted alphabetically by name and later split into further arrays in accordance to the first letter in the names. Any guide to carrying this out will be much appreciated, thanks. I am using the json kit via github and also NSJSONserialization.

 {
   "proj_name": "Ant",
   "id": 
      [
          {
             "name": "David"
          },
          {
             "name": "Aaron"
          }
      ]
 },
 {
    "proj_name": "Dax",
    "id": 
         [
           {
             "name": "Adrian"
           },
           {
             "name": "Dan"
           }
         ]
  }

Don't use JSON. Parse into arrays and dictionaries and deal with those. Forget it was ever JSON. — Hot Licks
– Hot Licks, Commented Jan 30, 2013 at 13:22
@HotLicks Why do you suggest that ? Would like to further understand — John Stone
– John Stone, Commented Jan 30, 2013 at 16:02
I'm saying, don't focus on the fact that it was JSON. Convert it to the Objective-C objects and figure out how to access those. — Hot Licks
– Hot Licks, Commented Jan 30, 2013 at 17:54

Vitalii Ivanov · Accepted Answer · 2013-01-30 12:59:36Z

3

Here is sample that selects just names and sort them alphabetically. Replace responseData with your data object.

NSMutableArray *names = [[NSMutableArray alloc] init];

NSError* error;
NSArray* json = [NSJSONSerialization 
    JSONObjectWithData:responseData
    options:kNilOptions 
    error:&error];

for (NSDictionary *proj in json) {
    NSArray *ids = [proj objectForKey: @"id"];

    for (NSDictionary *name in ids)
    {
        [names addObject: [name objectForKey: @"name"];
    }
}

NSArray *sortedNames = [names sortedArrayUsingSelector: @selector(localizedCaseInsensitiveCompare:)];

edited Jan 30, 2013 at 12:59

answered Jan 30, 2013 at 10:31

Vitalii Ivanov

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4 Comments

John Stone Over a year ago

Thank you @Madman :) I get a warning "Incompatible pointer types asigning to 'NSMutableArray *__strong' from NSArray", what seems to be the issue, i tried changing the NSArrays to NSMutableArrays also but that din't change anything

John Stone Over a year ago

sweet, thanks a lot!! that work I am able to see the correct outputs showing all the names in alphabetical other, I decided to display the values in a UIPickerView. It displays the first three names but not the forth

Vitalii Ivanov Over a year ago

Maybe you forgot to implement (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component ?

John Stone Over a year ago

I definitely did that using return [self.sortedNames count];

Siba Prasad Hota · Accepted Answer · 2013-01-30 10:20:22Z

3

Go to http://json.bloople.net/ in this link you can see the structure of your JSON response.

from the above response i can see the response as follow:

Project name: Dax

id : 0 name : Adrian

  1  name : Dan

So you can use the NSjsonserialization class from Apple. No need to use JSON kit.

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"Your URL"]]];
  NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

    NSLog(@"url=%@",request);

id jsonObject = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingAllowFragments error:nil];

if ([jsonObject respondsToSelector:@selector(objectForKey:)])

    {
    Nsstring *projectname=[jsonObject objectForKey:@"proj_name"];
    NSArray *name_array=[jsonObject objectForKey:@"id"];

     NSLog(@"projectname=%@",projectname);
     NSLog(@"name_array=%@",name_array);
    }

answered Jan 30, 2013 at 10:20

Siba Prasad Hota

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4 Comments

John Stone Over a year ago

Ahh I see Thank you Siba, I will give it a go and get back to you

pbibergal Over a year ago

Why would you do synchronous request and not asynchronous?

Siba Prasad Hota Over a year ago

it can be done Asynchronous Also. Just have to add the Delegate methods of NSURLconnection.

John Stone Over a year ago

@Siba If I wanted to go a step further and display the strings contained in the the "names_array" in a UIPickerView how can I accomplish that? I am using the methods: - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component // - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component

Matt Long · Accepted Answer · 2013-01-30 16:36:55Z

Assuming you've successfully parsed the JSON into an NSArray, you can simplify things pretty dramatically:

NSArray *names = [parsedArray valueForKeyPath:@"@distinctUnionOfArrays.id.name"];

The names array should now contain all of the names flattened into a single array. To sort them, you could then do:

NSArray *sortedNames = [names sortedArrayUsingDescriptors:@[[NSSortDescriptor 
                                      sortDescriptorWithKey:@"description" ascending:YES]]];

Or all at once:

  NSArray *sortedNames = [[parsedArray valueForKeyPath:@"@distinctUnionOfArrays.id.name"]
                          sortedArrayUsingDescriptors:@[[NSSortDescriptor 
                                                 sortDescriptorWithKey:@"description"
                                                             ascending:YES]]];

The sortedNames array would now contain:

<__NSArrayI 0x713ac20>(
Aaron,
Adrian,
Dan,
David
)

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