The easiest way to measure distance, time, altitude? Take two photos with the built-in camera app on your phone.
When you take a photo with your iPhone, it not only records the more than a thousand words, it also records the exact second you took it, your GPS position, altitude, heading, and speed. When you take two photos, maybe the difference between them could be used to create a handy stopwatch and a fast way to measure distances. Start and stop just by taking a photo.
