Firstly, if you love your phone more than your life, then you don't really need to read this. If you're about to use your smartphone in the wild, you gotta...broke it. Well, still better than be dead, right.
There are a bunch of useful things in your phone: speaker, LCD screen, metal, wire, circuit board and battery. Check the picture to see where you can find them:
To start the fire, you will need the wire and the battery from your phone. Touch the wire to the positive and negative nodes. This will become hot immediately. Be sure to have some combustible material to make the fire.
You can also cut tools and make a "knife" from your smartphone. you will need a metal mount and a circuit board. Aslo bring some rock to sharpen your knife.
To call the help, or signalize the airplane flying by, you can make a signal mirror using the LCD screen from your phone. This is an effective way to signalize.
To make a compass, you need a magnet from your speaker. You will also need the wire, puddle and a leaf that you have to find in the environment.
Have you ever thought of catching the food with your circuit board? Well, this may become reality someday. I believe a rock may be more comfortable to work with in certain ways, though.