Escaping diacritics in a UTF8 string from C/Obj-C to javascript

First, a brief expl开发者_Python百科anation of why I'm doing this:

I'm loading strings from XML, and using these to interact with existing javascript functions. I need to escape them, only because I'm using the webview's stringByEvaluatingJavaScriptFromString method.

I'm using this escape function:

- (NSString *) stringByEscapingMetacharacters
{    
    const char *UTF8Input = [self UTF8String];
    char *UTF8Output = [[NSMutableData dataWithLength:strlen(UTF8Input) * 4 + 1  /* Worst case */] mutableBytes];
    char ch, *och = UTF8Output;

    while ((ch = *UTF8Input++))
        if (ch == '\'' || ch == '\'' || ch == '\\' || ch == '"')
        {
            *och++ = '\\';
            *och++ = ch;
        } 
        else if (isascii(ch))
            och = vis(och, ch, VIS_NL | VIS_TAB | VIS_CSTYLE, *UTF8Input);
        else
            och+= sprintf(och, "\\%03hho", ch);
    return [NSString stringWithUTF8String:UTF8Output];
}

It works fine, except for diacritics. For example, "é" shows up as "é"

So, how can I escape the diacritics?

You need to implement proper UTF-8 sequences escapement. Something like this:

if (ch == '\'' || ch == '\'' || ch == '\\' || ch == '"')
{
    *och++ = '\\';
    *och++ = ch;
} 
else if (((unsigned char)ch & 0xe0) == 0xc0) // 2 byte utf8 sequence
{
    *och++ = ch;
    *och++ = UTF8Input++;
}
else if (((unsigned char)ch & 0xf0) == 0xe0)  // 3 byte utf8 sequence
{
    *och++ = ch;
    *och++ = UTF8Input++;
    *och++ = UTF8Input++;
}
else if (isascii(ch))
     och = vis(och, ch, VIS_NL | VIS_TAB | VIS_CSTYLE, *UTF8Input);