判断是否emij表情

// 判断是否是 emoji表情

- (BOOL)isEmoji
{
     BOOL returnValue = NO;
    if (self == nil || [self isKindOfClass:[NSNull class]] || [self isEqualToString:@""] || ([self isKindOfClass:[NSString class]] && self.length<2))
    {
        return returnValue;
    }
         
     const unichar hs = [self characterAtIndex:0];
     // surrogate pair
     if (0xd800 <= hs && hs <= 0xdbff) {
         if (self.length > 1) {
             const unichar ls = [self characterAtIndex:1];
             const int uc = ((hs - 0xd800) * 0x400) + (ls - 0xdc00) + 0x10000;
             if (0x1d000 <= uc && uc <= 0x1f77f) {
                 returnValue = YES;
             }
         }
     } else if (self.length > 1) {
         const unichar ls = [self characterAtIndex:1];
         if (ls == 0x20e3) {
             returnValue = YES;
         }
     } else {
         // non surrogate
         if (0x2100 <= hs && hs <= 0x27ff) {
             returnValue = YES;
         } else if (0x2B05 <= hs && hs <= 0x2b07) {
             returnValue = YES;
         } else if (0x2934 <= hs && hs <= 0x2935) {
             returnValue = YES;
         } else if (0x3297 <= hs && hs <= 0x3299) {
             returnValue = YES;
         } else if (hs == 0xa9 || hs == 0xae || hs == 0x303d || hs == 0x3030 || hs == 0x2b55 || hs == 0x2b1c || hs == 0x2b1b || hs == 0x2b50) {
             returnValue = YES;
         }
     }
    
    return returnValue;
}