Question

I use the following code to create a JSON file.

// Some data in keys and vals.
NSDictionary* dictionary = [NSDictionary dictionaryWithObjects:vals forKeys:keys];
NSError* writeError = nil;
NSData* jsonData = [NSJSONSerialization dataWithJSONObject:dictionary 
                   options:NSJSONWritingPrettyPrinted error:&writeError];   
NSString* path = @"json.txt";
[jsonData writeToFile:path atomically:YES];

How can I output a JSONP file? Is there a Cocoa framework I can use?

Update: In the meantime, I used a quick-and-dirty solution: I read in the JSON file just written before to the disc and add the missing JSONP-function to the string. Then, I write the file a second time. I think that’s not worth being the answer to my question. So I will leave this question open to a smarter solution.

Answer 1

You could convert the JSON data to a string, wrap it in your function call and then write it to a file. Example:

NSData* jsonData = [NSJSONSerialization dataWithJSONObject:dictionary 
                                                   options:NSJSONWritingPrettyPrinted 
                                                     error:NULL];
NSMutableString *jsonString = [[[NSMutableString alloc] initWithData:jsonData 
                                                            encoding:NSUTF8StringEncoding] autorelease];
[jsonString insertString:@"functionCall(" atIndex:0];
[jsonString appendString:@");"];
[jsonString writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:NULL];

(I’m using a mutable string here for better memory efficiency.)