The Kindle app for iOS updated in version 3.8

With the Kindle app optimized for the iPad, iPhone, and iPod touch, you can read Kindle books, newspapers, magazines,
textbooks and PDFs.

Henceforth the new version 3.8 brings:  Line Spacing, Multipage Highlights, Print Replica Textbooks notebook improvements, Accessibility Improvements and Bug Fixes/Stability Improvements.