Memories Book is a free app for iOS that is FamilySearch compatible. This app allows you to login to your FamilySearch account and generate a memories book with 4-5 generations of photos, stories, and ancestors from your Family Search Family Tree.
The first time you generate a book it will default to the root person associated with the FamilySearch login used in the app. Subsequent books can start with any root individual on your tree.
Free and Fee Versions
FREE: Downloads of any Memories Book(s) to your phone or iOS device
FEE: $4.99 to download a PDF file but this fee gives you unlimited downloads thru the app on your phone. That means you can download a memory book for 4 generations, then another 4 generations, specify a specific family line, etc, all for a one-time download fee of $4.99.