If you're using WhatsApp on your iPhone, you may need an easy way to save WhatsApp message history to printable format for various purpose. iBackup Viewer is the exact app to do such work for you. What you need to do is just few clicks.
Then choose the backup you've created with iTunes in the left side navigation panel, expand it and select "WhatsApp".
(The item "WhatsApp" may not appear if the backup does not contain WhatsApp)
Choose "Save to PDF..." if you'd like to save the messages to PDF file
or "Print..." if you just want to print it out to paper.
Optionally, you can save the messages to well formatted HTML files by selecting "Export to HTML...".