Where to look for mobile app making info

Hi everyone,

I have a project I would like to make in conjunction with a mobile app. Basically I will be making a container with a number of compartments, I would like to be able to monitor these compartments and find out if (and when) they have been opened.

I would like to build an app with a simple GUI, a grid of squares for example. When the compartment is open perhaps the corresponding square would change colour and a timestamp may be displayed... For example.

What I would like to know is what people may suggest is a good way of getting started with this project, where to look and any advice would be greatly appreciated. I am keen to learn and research, at the moment I just feel a bit lost as to where I should begin. 

I understand making apps for android is much more financially viable, someone once told me it is much more expensive through the Apple app store. 

So please, and books, youtube videos, forums, websites you can recommend for a beginner in this field who is keen to learn.

Best,

Henri