sample file have a problem in page 6.
there is problem that can not expression in anroid platform.
also you can check problem that can see chinese font in iOS plarform.
probably i think it has font issue.
please check it
it seems that the font used in page 6 is not embedded in the pdf file.
You could embed the font on your file or add it to iOS project.
To add a font you could take a look at this Knowledge Base Article: www.radaeepdf.com/support/knowledge-base?view=kb&kbartid=56
The Android version uses Noto font as default font (that includes also Korean characters), for that reason you are able to render the page correctly.