NSString with \0

Question

What is the best way to initiate NSString that contains @"\0"?

NSString* foo = @"bar\0";

causes 'CFString literal contains NUL character' warning.

Answer 1

NSString objects are for text. Consider using an NSData or NSMutableData object if you wish to have non-text data in amongst textual data (for example, when it is to be written to a socket or saved to a file).

Answer 2

You can put a NUL character into an NSString instance, here's one example:

int main() {
    NSString *string = [NSString stringWithFormat: @"Hello%CWorld!", 0];
    NSData *bytes = [string dataUsingEncoding: NSUTF8StringEncoding];
    NSLog(@"string: %@", string);
    NSLog(@"bytes: %@", bytes);
    return 0;
}

Be aware that at surprising points in your app's execution, the string will be converted into a C string (or something similar) for interacting with lower-level API, and that this will cause the string to be truncated. As an example, the output of the above program is this:

2011-06-02 09:18:30.307 Untitled[294:707] string: Hello

2011-06-02 09:18:30.309 Untitled[294:707] bytes: <48656c6c 6f00576f 726c6421>

Showing that the NSString itself is completely intact but that NSLog() won't display it correctly.