Building an Android Mobile App
I choose to use Xamarin because it was cross platform. I read that you can develop in 1 language and it will compile in Android, iOS, and Windows mobile. However, I ran into many snags along the way and ended up focusing on Android. To develop for Apple you really do need an Apple computer, Xamarin/Visual Studios will not compile without one. Using the slow Emulator I was able to deploy to the OS. However it is faster if you have the physical device connected to your PC. Yet, be warned that not all cables will do the job. I went through 3 cables and the last one finally work. If you can transfer files to the PC then that cable should work for debugging.
You first start with creating the UI. Within the folder tree you have axml files (add one as needed). These files are the visual representations that the user will see. The code is like XML but tailored to add objects to the screen. You can add a layout then a button or an image and it will generate the visuals. Toggle between DESIGNER and SOURCE till you get something that looks stunning.
Each UI page will have a matching C# page, or VB. From there I wrote C# and made the app function. I was able to use certain android features such as the date and time picker object. Which might look different based on the phone you have. In this case when you click the textbox it opens the diolog then sends the values back to that textbox. Very user friendly way of getting someone to enter info. Cause no one wants to type the date and time.
The service that runs in the background can be started and stopped with a button (new Intent(this, typeof(Service));). If no interval is selected it will throw an error using the AlertDialog.
The service makes a call to the web sites API using what VS calls a Web Reference, in which I added. Visual Studios makes it easy to add the Web Reference and it even builds the methods from that API for you. The method takes the values entered by the user and passes them to the Web Reference, the Web Reference, sends to the asmx file (which is hosted on the web) and it returns an int of 0 or 1. 1 meaning success, web site updated, the user gets a message on screen.
The last aspect of this app that I want to talk about would be the ILocationListener. This Android specific library allows you to tap into the GPS system that is already on your phone. The code used detects when the phone has moved by 1 meter and updates your lat and long. Then every set interval (1 min / 5 mins / 15 mins / 30 mins / 1 hr) the lat and long is geocoded into a readable location, address, city, and state.
All in all there are many parts to this simple app. By utilizing web services, Xamarin, the service class, ILocationListener, and C# I was able to make a tracking app that sends locations back to our web site.
thanks for reading !!