如果项目中有评论或者信息恢复的地方，往往会用到emoji，有时候如后台不支持emoji，就会显示乱码错误，我们可以把emoji转成unicode编码或者utf8编码格式传给服务器。当然如果后台服务器接收的时候能做好判断识别最好，我们这边后台是支持的，我仅记录一下方法，以备不时之需。

先定义一个UITextView 并设置代理
设定一个宏定义，用来判断emoji
<pre>

define MULITTHREEBYTEUTF16TOUNICODE(x,y) (((((x ^ 0xD800) << 2) | ((y ^ 0xDC00) >> 8)) << 8) | ((y ^ 0xDC00) & 0xFF)) + 0x10000

</pre>
下面写代理方法实现的内容
<pre>

• (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
  {
  NSString *hexstr = @"";

  for (int i=0;i< [text length];i++)
  {
  hexstr = [hexstr stringByAppendingFormat:@"%@",[NSString stringWithFormat:@"0x%1X ",[text characterAtIndex:i]]];
  }
  NSLog(@"UTF16 [%@]",hexstr);

  hexstr = @"";

  long slen = strlen([text UTF8String]);

  for (int i = 0; i < slen; i++)
  {
  //fffffff0 去除前面六个F & 0xFF
  hexstr = [hexstr stringByAppendingFormat:@"%@",[NSString stringWithFormat:@"0x%X ",[text UTF8String][i] & 0xFF ]];
  }
  NSLog(@"UTF8 [%@]",hexstr);

  hexstr = @"";

  if ([text length] >= 2) {

    for (int i = 0; i < [text length] / 2 && ([text length] % 2 == 0) ; i++)
    {
        // three bytes
        if (([text characterAtIndex:i*2] & 0xFF00) == 0 ) {
            hexstr = [hexstr stringByAppendingFormat:@"Ox%1X 0x%1X",[text characterAtIndex:i*2],[text characterAtIndex:i*2+1]];
        }
        else
        {// four bytes
            hexstr = [hexstr stringByAppendingFormat:@"U+%1X ",MULITTHREEBYTEUTF16TOUNICODE([text characterAtIndex:i*2],[text characterAtIndex:i*2+1])];
        }
        
    }
    NSLog(@"(unicode) [%@]",hexstr);
  

  }
  else
  {
  NSLog(@"(unicode) U+%1X",[text characterAtIndex:0]);
  }

  return YES;
  }
  </pre>