Отправка СМС через приложение

if ([[[UIDevice currentDevice] systemVersion] doubleValue ] >= 4.0) {
    MFMessageComposeViewController *controller = [[MFMessageComposeViewController alloc] init];
    if ([MFMessageComposeViewController canSendText]) {
        controller.body = str;
        controller.recipients = nil;
        controller.messageComposeDelegate = self;
        [self presentViewController:controller animated:YES completion:nil];
    }
}