判断是否是 emoji表情

+ (BOOL)stringContainsEmoji:(NSString *)string
{
    __block BOOL returnValue = NO;
    [string enumerateSubstringsInRange:NSMakeRange( 0 , [string length]) options:NSStringEnumerationByComposedCharacterSequences usingBlock:
     ^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {

         const unichar hs = [substring characterAtIndex: 0 ];
         // surrogate pair
         if ( 0xd800 <= hs && hs <= 0xdbff ) {
             if (substring.length > 1 ) {
                 const unichar ls = [substring characterAtIndex: 1 ];
                 const int uc = ((hs - 0xd800 ) * 0x400 ) + (ls - 0xdc00 ) + 0x10000 ;
                 if ( 0x1d000 <= uc && uc <= 0x1f77f ) {
                     returnValue = YES;
                 }
             }
         } else if (substring.length > 1 ) {
             const unichar ls = [substring 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;
}