NSInvalidArgumentException when using a value extracted from JSON data - iphone

Question

I am trying to retrieve value for id:
{"id":1,"name":"XYZ"}
When I use:
NSString *jsonData = [[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:url]];
NSArray * myPeople = [jsonData JSONValue];
NSString *name = [[NSString alloc] init];
NSDictionary *person = [myPeople objectAtIndex:[indexPath row]];
name = [NSString stringWithString:[person valueForKey:#"id"]];
name = [name stringByAppendingString:#". "];
name = [name stringByAppendingString:[person valueForKey:#"name"]];
name = [name stringByAppendingString:[person valueForKey:#"id"]];
cell.textLabel.text = name;
I get the following error:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException'
reason: '-[NSCFNumber length]: unrecognized selector sent to instance 0x4e7f8b0
How can I fix this?

Answer 1

You are calling both stringWithString: and stringByAppendingString: but then passing in an NSNumber
You need to get the string value of the NSNumber
[[person valueForKey:#"id"] stringValue];
or use a format like:
name = [NSString stringWithFormat:#"%#%#", name, [person valueForKey:#"id"]];
I would also consider changing the structure slightly to make it easier to follow like this:
NSDictionary *person = [myPeople objectAtIndex:[indexPath row]];
NSString *personName = [person valueForKey:#"name"];
NSSNumber *personId = [person valueForKey:#"id"];
NSString *name = [NSString stringWithFormat:#"%#. %# %#", personId, personName, personId];
For sorting you want to make sure you are not pulling that data every time you set up a cell (looks like you are) or it will be a terrible experience.
I'm sure someone can point you to a better way of sorting but the quickest thing I can think of is
NSArray *myPeople = [[jsonData JSONValue] sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [[obj1 objectForKey:#"id"] compare:[obj2 objectForKey:#"id"]];
}]