UITextView 禁止换空行

当前行输入文字后可以换下一行，当前行无文字禁止用户换行

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {    //禁止空行    NSString *result = [textView.text stringByReplacingCharactersInRange:range withString:text];    if ([result rangeOfString:@"\n\n"].location != NSNotFound) {        return NO;    }    return YES;}