Publish a book to Apple Books in Pages on iPhone
You can use Pages to save your book as an EPUB file, with cover art and formatting optimized for publishing on Apple Books.
Before you get started, here are a few things to keep in mind:
iTunes Connect account: To publish on Apple Books, you first need to set up an iTunes Connect account. iTunes Connect is a website that allows you to distribute and manage books on Apple Books. If you aren’t ready to distribute your book yet, you can also list it as a pre-order if you’d like to start advertising it.
Table of contents: Most books need to include a table of contents that readers can use to navigate. To set up a book so that Pages can create a table of contents, apply paragraph styles to the headings or chapters in the book. When Pages generates the EPUB file, a table of contents is automatically created based on those paragraph styles. To check the table of contents, tap the page number at the bottom of the screen, then tap Table of Contents. See Create a table of contents.
International Standard Book Number (ISBN-13): You don’t need an ISBN-13 to publish to Apple Books, but if you have one, have it ready, as you can only enter it the first time you submit a book. If you’re self-publishing a book, you can apply for and obtain an ISBN from the ISBN registration agency where you’re based.
Go to the Pages app
on your iPhone.Open the document you want to publish as a book.
Tap
in the toolbar, tap Export, then tap Publish to Apple Books.Enter the requested information:
Title and Author: Enter the title and author you want readers to see if you publish it.
Cover: Use the first page of the document, choose a PDF or image file, or choose to use no book cover. You can also choose to export the covers as a separate image file.
Layout: For a word-processing document, you can choose “Fixed layout” to preserve the layout of the page, or Reflowable so readers can adjust the font size and style (which may change how much content is visible on each page). Page layout documents can use only a fixed layout.
Sample: To save a sample of your book as a separate file to upload to Apple Books, select “Export a sample of your book,” then choose which pages to include.
Tap Export.
If Pages made changes to your document while exporting the EPUB file (for example, the cover image was resized to follow Apple Books guidelines), they are listed in the Export Details dialog. Tap Continue to dismiss the Export Details dialog.
Tap Save to Files (you may need to scroll down first), choose where to save the EPUB file, then tap Save.
The filename extension .epub is automatically appended to the file name.
Do one of the following:
Preview your book: Tap Go to Files
app, then tap your book’s exported EPUB file to view it in the Books 
app.Upload your book to Apple Books: Tap Go to Publishing Portal, then sign in with your iTunes Connect account (or create an account if you don’t have one).
Return to your document: Tap Done.
Your book must be reviewed and approved before it’s available on Apple Books. You can check the status of the book in My Books on iTunes Connect.
For more information about publishing to Apple Books, see this Apple Support article or Apple Books Formatting Guidelines. For information about writing, publishing, marketing, and selling your book on Apple Books, see authors.apple.com.