Converting NSData to NSDictionary

You have to convert NSDatainto UTF8 before parsing it using NSJSONSerialization.

NSError* error = nil;

NSString *strISOLatin = [[NSString alloc] initWithData:data encoding:NSISOLatin1StringEncoding];
NSData *dataUTF8 = [strISOLatin dataUsingEncoding:NSUTF8StringEncoding];

id dict = [NSJSONSerialization JSONObjectWithData:dataUTF8 options:0 error:&error];
if (dict != nil) {
    NSLog(@"Dict: %@", dict);
} else {
    NSLog(@"Error: %@", error);
}