Calculate text width on iPhone

    NSString *message = [NSString stringWithUTF8String: "Hello"];
    
    int      count = [message length];
    UniChar *characters = (UniChar *) malloc(count * sizeof(UniChar));
    CGGlyph *glyphs     = (CGGlyph *) malloc(count * sizeof(CGGlyph));
    int     *advances   = (int     *) malloc(count * sizeof(int	  ));
    CGSize  *cgAdvances = (CGSize  *) malloc(count * sizeof(CGSize));
    
    /* Get the characters, glyphs and advances and calculate aStringWidth. */
    [message getCharacters: characters];
	CGFontGetGlyphsForUnichars(font, characters, glyphs, count);
    CGFontGetGlyphAdvances(font, glyphs, count, advances);
    int unitsPerEm = CGFontGetUnitsPerEm(font);

    int i;
    for (i = 0; i < count; i++)
    {
        NSLog(@"glyph[%d] = %u, advances[%d] = %d\n", i, glyphs[i], i, advances[i]);
        cgAdvances[i].width = advances[i] * fontSize / unitsPerEm;
        NSLog(@"advance: %g", cgAdvances[i].width);
        cgAdvances[i].height = 0;
    }