To use just ask a Yes/No question and shake to phone to get the prediction.
Don't ask the same question or you will confuse the "complex prediction algorithm" :-)
MyCrystalBall is a hybrid mobile application developped using AngularJS and the Ionic Framework. It's an application developed for demonstrating how to build a mobile application from 0 using the 2 frameworks.
You can find the complete, step by step guide on how this application was developed here:
You also have full access to the source code.