I'm writing a pdf reader iPhone application.

I know how to show pdf file in view using CGPDF** classes in iOS.

What I want to do now is to search text in pdf file, and highlight the searched text. So, I need a library which can detect what text is in what position. Besides, I want the library able to handle unicode and Chinese characters.

I've searched for a few days but still cannot find anything suitable.

I've tried xpdf, but it is written in c++. I don't know how to use c++ code in iPhone app.

I've also tried http://www.codeproject.com/KB/cpp/ExtractPDFText.aspx but it does not handle Chinese characters.

I've tried to code by myself, but the encoding in PDF is really complicated.

For example, I don't know what to refer to when I want to decode the text by the following font:

8 0 obj
<< /Type /Font /Subtype /Type0 /Encoding /Identity-H /BaseFont /RNXJTV+PMingLiU
/DescendantFonts [ 157 0 R ] >>
endobj

157 0 obj
<< /Type /Font /Subtype /CIDFontType2 /BaseFont /RNXJTV+PMingLiU /CIDSystemInfo
<< /Registry (Adobe) /Ordering (CNS1) /Supplement 0 >> /FontDescriptor 158 0 R
/W 161 0 R /DW 1000 /CIDToGIDMap 162 0 R >>
endobj

158 0 obj
<< /Type /FontDescriptor /Ascent 801 /CapHeight 711 /Descent -199 /Flags 32
/FontBBox [0 -199 999 801] /FontName /RNXJTV+PMingLiU /ItalicAngle 0 /StemV
0 /Leading 199 /MaxWidth 1000 /XHeight 533 /FontFile2 159 0 R >>
endobj