How to “pass on” a variable number of arguments to NSString’s +stringWithFormat:

initWithFormat:arguments:

NSString *estr(NSString *format, ...) {
    va_list args;
    va_start(args, format);
    NSString *s = [[[NSString alloc] initWithFormat:format arguments:args] autorelease];
    va_end(args);
    return s;
}

they don’t seem to have a convenience constructor “stringWith…” version