NSASCIIStringEncoding breaks

It is possible that [subject stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding], may return null, if subject contains ASCII charter out side 0 to 127.

NSString *mailString = [NSString stringWithFormat:@"mailto to=%@&subject=%@&body=%@",
[to stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding],
[subject stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding],
[body stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]];

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:mailString]];

To stop this we can use an simple filter like.
-(NSString *)replaceLatin NSString *)string{

return [[[[[[[[[[[[string stringByReplacingOccurrencesOfString:@"–" withString:@""] stringByReplacingOccurrencesOfString:@”—” withString:@”"] stringByReplacingOccurrencesOfString:@”¡” withString:@”"] stringByReplacingOccurrencesOfString:@”¿” withString:@”"] stringByReplacingOccurrencesOfString:@””” withString:@”"] stringByReplacingOccurrencesOfString:@”“” withString:@”"] stringByReplacingOccurrencesOfString:@”\”" withString:@”"] stringByReplacingOccurrencesOfString:@”‘” withString:@”"] stringByReplacingOccurrencesOfString:@”’” withString:@”"] stringByReplacingOccurrencesOfString:@”‘” withString:@”"] stringByReplacingOccurrencesOfString:@”«” withString:@”"] stringByReplacingOccurrencesOfString:@”»” withString:@”"];
}