parsing JSON of webservice on objective c array - iphone

Question

I'm developing an iphone app and I have a JSON from web service as below:
[
{
"0":"test_w",
"assignment_title":"test_w",
"1":"2011-11-02 04:02:00",
"assignment_publishing_datetime":"2011-11-02 04:02:00",
"2":"2011-11-02 01:53:00",
"assignment_due_datetime":"2011-11-02 01:53:00",
"3":"course_math.png",
"course_icon":"course_math.png",
"4":null,
"submission_id":null
},
{
"0":"\u062a\u0637\u0628\u064a\u0642 \u0631\u0642\u0645 3",
"assignment_title":"\u062a\u0637\u0628\u064a\u0642 \u0631\u0642\u0645 3",
"1":"2011-08-08 00:00:00",
"assignment_publishing_datetime":"2011-08-08 00:00:00",
"2":"2011-08-25 00:00:00",
"assignment_due_datetime":"2011-08-25 00:00:00",
"3":"course_math.png",
"course_icon":"course_math.png",
"4":null,
"submission_id":null
}
]
also I have a tableview and I need to parser assignment_title only on the tableview cells , also I'm using SBJSON library.
so what is the best way to extract assignment_title and put them on cells?

Answer 1

I find the solution from your answers as below:
I created a method with 2 parameters (json_path , field [that i need to show in tableview cell])
- (NSMutableArray*)JSONPath:(NSString *)path JSONField:(NSString *)field{
SBJSON *parser = [[SBJSON alloc] init];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:path]];
// Perform request and get JSON back as a NSData object
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
// Get JSON as a NSString from NSData response
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
NSArray *statuses = [parser objectWithString:json_string error:nil];
NSMutableArray * tempMutArray = [[[NSMutableArray alloc] init] autorelease];
int i;
for (i=0; i<[statuses count]; i++) {
[tempMutArray addObject:[[statuses objectAtIndex:i] objectForKey:field]];
}
return [tempMutArray copy];
}
after that i call it in cell as following:
//in viewDidLoad
NSArray * homework = [self JSONPath:#"http://....." JSONField:#"assignment_title"];
//In cellForRowAtIndexPath
cell.textLabel.text = [homework objectAtIndex:indexPath.row];
Thanks to all

Answer 2

If you are doing it through NSJSONSerialization you can get array of assignment_title using this simple method ;)
NSError *error = nil;
NSData *jsonData = [NSData dataWithContentsOfURL:apiURL];
id jsonObjectFound = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&error];
NSArray* assignmentTitles = [jsonObjectFound valueForKey:#"assignment_title"];

Answer 3

If performance matters, you might consider using an ASIHTTPRequest to fetch the json asynchronously, then inside the requestFinished: you might do something like:
- (void)requestFinished:(ASIHTTPRequest *)request
{
// Use when fetching text data
NSString *responseString = [request responseString];
//assuming you created a property instance variable NSArray *myArrAssignmentTitles
NSArray *tempArray = [responseString JSONValue];
//making an array of assignment_title
NSMutableArray *tempMutArray = [[NSMutableArray alloc] init];
int i;
for(i = 0;i < [tempArray count];i++){
[tempMutArray addObject:[[tempArray objectAtIndex:i] objectForKey:#"assignment_title"]];
}
//assign the data to the instance variable NSArray *myArrAssignmentTitles
self.myArrAssignmentTitles = tempMutArray;
//release tempMutArray since the instance variable has it
[tempMutArray release];
//call the reload table
[self.tableView reloadData];//i think this is how to reload the table
}
- (void)requestFailed:(ASIHTTPRequest *)request
{
NSError *error = [request error];
}
So, your myArrAssignmentTitles has all the values assignment_title from json
all you do is just apply the array data for the cell e.g.
cell.textLabel.text = [self.myArrAssignmentTitles objectAtIndex:indexPath.row];
its a long code sorry about that. But, thats works for me xD; it fetches the json asynchronously after that it creates an array of assignment_title hopes it helps.