Hands-on experience, preferably with an expert who can field questions and catch your mistakes before they hurt (too much), will always be one of the best ways to learn wilderness skills. But if you're willing to put in the time and practice to figure out what actually works, you can learn from just about anything -- books, online content, tips scribbled on the inside of a gum wrapper... and smartphone apps.
Below is a list of the most promising wilderness survival apps for both Android and iOS devices. Of course, reading about what to do if things go wrong on your hike isn't going to help you nearly as much as actually practicing the skill until you get it right. So whatever you take from these apps, make sure you practice, practice, practice. That's the best way to sort good advice from the bad, figure out what works for you (I still can't light a fire with a bowdrill to save my life -- scratch that one off my list of survival skills), and be able to reproduce said skills when the chips are down.
(Apps are listed in alphabetical order)
Based on the U.S. Army Field Manual 21-76. Includes information on all the basics -- food, water, fire, shelter -- plus first aid, identifying plants, animals, navigation, survival psychology, and so on. Looks a lot like U.S. Army Survival Guide Pro for Android.
Based on the same version of the Army Survival Manual as U.S. Army Survival Guide Pro, but free. Looks like it comes straight from the survival manual, whereas screenshots from U.S. Army Survival Guide Pro show an easier-to-read format.
I was a little skeptical of this because it comes from a TV personality, but it gets good ratings. On the other hand, it's also full of a lot of things you don't necessarily need to know before hiking, like quotes and Grylls' own fitness program. (Users also warn that this app is very resource intensive, so I'd save it for recreational reading and practice at home.)
Based on multiple military survival manuals. You can probably skip the sections on parachuting, camouflage, self-defense and military driving, but it has lots of useful information you could definitely use on the trail, including acquiring the essentials for survival, traps and snares, edible plants, and so on.
*I'm not sure when the "free" offer expires.
The title link takes you to the Android app; click here for the iOS version.
Written by a former SAS soldier and instructor, includes information on surviving in extreme climates, navigation, edible, medicinal and poisonous plants, etc. Also includes video content and survival checklists.
Based on U.S. Army survival manuals, this app takes you through the basics: Navigating, signaling for help, acquiring food, water, shelter and heat, and so on. I believe this is based off an older version of the manual than the other Army-based manuals I've listed here, but the information is still useful. If it build a fire in ye olde 1900s, it'll still build a fire today.
Another one based on the U.S. Army Survival Guide; as you'd expect, this app teaches you to do everything from starting a fire to finding food, water and shelter. As with most military references there'll be some information that just doesn't apply to hiking, but plenty that does.
Also available in a free version with ads. It sounds like the free version might not let you store everything offline, but the paid version does.
Obviously for use in cold climates -- covers fishing, tracking, snares, and so on, plus some combat-oriented skills you'll hopefully never need, but still make for interesting reading.
One of the nicest interfaces I've seen on a survival app. Lots of instructional video, and it includes first aid information and "the latest" survival techniques based on military training.