Start with high-confidence mobile app development books, then narrow by subgenre or adjacent topics.
Bluetooth Low Energy
Robin Heydon
Android Programming
Bill Phillips, Chris Stewart
iOS Programming
Christian Keur, Aaron Hillegass
Android App Development for Dummies
Michael Burton
Flutter for Dummies
Barry Burd
Android Application Development All-in-one for Dummies
Barry Burd, John Paul Mueller
Android Smartphones for Seniors for Dummies
Marsha Collier
iOS 5 Programming Cookbook
Vandad Nahavandipoor
Android Cookbook
Ian Darwin
Learning Cocoa With Objective-c
Paris Buttfield-Addison, Jonathon Manning
Head First Swift
Jonathon Manning, Paris Buttfield-Addison
iOS 7 Programming Fundamentals
Matt Neuburg
Unity Game Development Cookbook
Head First Android Development
Dawn Griffiths, David Griffiths
Learn Java the Easy Way
Bryson Payne
Unity in Action
Joe Hocking
iOS Development With Swift
Craig Grummitt
Hello, Android
Ed Burnette
