Does converting NSString to NSData force a trailing byte?

Question

This is in response to this incorrect answer: https://stackoverflow.com/a/7894952/192819

Does converting NSString like this:

NSString *str = @"teststring";
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

force a trailing \0 byte, which means

-[NSJSONSerialization:JSONObjectWithData:] 

and others will fail unless you remove it.

Answer 1

No, it does not. See this example:

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
                      @"v1", @"k1", 
                      @"v2", @"k2",
                      nil];
NSLog(@"dict=%@", dict);

NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:0 error:nil];    

NSString *jsonAsString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

NSData *jsonDataFromString = [jsonAsString dataUsingEncoding:NSUTF8StringEncoding];

// DO NOT DO THIS:
// jsonDataFromString = [jsonDataFromString subdataWithRange:NSMakeRange(0, [jsonDataFromString length] - 1)];

NSDictionary *jsonObject = [NSJSONSerialization JSONObjectWithData:jsonDataFromString options:0 error:nil];
NSLog(@"jsonObject=%@", jsonObject);

Try it, and then try it with the "DO NOT DO THIS" line uncommented. You will see there is no problem.