Looking for an app to write infoo about my books

Have you considered Microsoft Excel or Apple Numbers? Perhaps this will satisfy the need for tracking so many different characters, environments, etc.

most of this app is accessible. the price is more than other options. also, there is an entry about scrivener in the forums on this site. here is the app store description:
*** Featured in App Store Best of 2016 ***
“The biggest software advance for writers since the word processor.” —Michael Marshall Smith, bestselling author
Typewriter. Ring-binder. Scrapbook. Scrivener combines all the writing tools you need to craft your first draft, from nascent notion to final full stop.
Tailor-made for creating long manuscripts, Scrivener banishes page fright by allowing you to compose your text in any order, in sections as large or small as you like. Got a great idea but don’t know where it fits? Write when inspiration strikes and find its place later. Grow your manuscript organically, idea by idea.
Whether you plan or plunge, Scrivener works your way: meticulously outline every last detail first, or hammer out a complete draft and restructure later. Or do a bit of both. All text sections in Scrivener are fully integrated with its outlining tools, so working with an overview of your manuscript is only ever a tap away, and turning Chapter Four into Chapter One is as simple as drag and drop.
Need to refer to research? In Scrivener, your background material is always at hand. Write a description based on a photograph. Reference a video or PDF. Check for consistency with an earlier chapter. On the iPad, open two documents side-by-side; on the iPhone, flip between research and writing with just two taps.
Once you’re ready to share your work with the world, simply compile everything into a single document for printing, or export to popular formats such as Word, PDF, Final Draft or plain text. You can even share using different formatting, so that you can write in your favorite font and still keep your editor happy.
FEATURES
Get Started
• Interactive tutorial project
• Keep each manuscript and supporting materials in a self-contained project
• Import Word, RTF, Final Draft and plain text files
• Easily split imported text into separate sections
Get Writing
• Write your manuscript in sections of any size
• View all sections as a single text using the “Draft Navigator” (iPad only)
• Quickly navigate sections using the “binder” sidebar
• Format with fonts and presets
• Comments, footnotes, links and highlights
• Simple bullets and lists
• Insert images
• Pinch-zoom to resize text
• Full-screen mode (iPad only)
• Typewriter scrolling mode keeps typed text center-screen (iPad only)
• Write a screenplay using scriptwriting mode
• Live word and character counts
• Set word and character count targets
• Find and replace
• Customizable keyboard row provides quick-access buttons for formatting, navigation and punctuation
• Comprehensive keyboard shortcuts for external keyboard users
• Dark mode
Find Your Structure
• Write in any order and reorganize later
• Write a synopsis for any text section and see it in the outline
• Expand, collapse and drill down into sections of your project
• Rearrange sections as index cards on the corkboard (iPad only)
• Project-wide search
• Track ideas using labels and status
• Apply custom icons to your sections
Refer to Research
• Import research material such as image, PDF and media flies
• View research files or other sections right alongside your writing (iPad only)
• Every section has its own notes area for jotting down ideas
• Supports multi-tasking split screen mode (supported devices only)
Share Your Work
• Compile to a single document for sharing or printing
• Use different formatting in your exported or printed document
• Export to Word, RTF, Final Draft, PDF or plain text
• Convert rich text to Markdown for sharing with Markdown apps
• Create and email zipped backups of your projects
Work Anywhere
• Use Dropbox to sync between devices and with the macOS and Windows versions of Scrivener*
• Copy projects between devices via iTunes
* Requires a Dropbox account (not compatible with iCloud).
SUPPORT
You can contact us at ios.support@literatureandlatte.com, visit our forums at http://www.literatureandlatte.com/forum, or find us @scrivenerapp on Twitter.

as you can see from the app description, the kind of tracking is much better on the iPad than the iPhone.