Nowadays Coders Struggle
Ten years ago it was great to develop software - Java and Flash applications were the must have multi-platform tech and that was it.
So, the question here is: Why do IDE (Integrated Development Environment) software industries are making so hard to develop multi-platform software?
Let's face it - Today, if you want to release a multi-platform software, you will need to learn: Objective-C (Apple, IOs), C# (Microsoft) and Java (Android) at minimum.
What about the investment?
10 Years ago was easy to launch some software with great power just with one IDE and Programing Language. I did hundreds of pure Flash/ActionScript, Java and HTML/JS/CSS applications.
You can choose between pay to develop your codes on an online coding service where you will be able to publish your software to multi-platforms (paying a price), or:
1. Apple computer: If you want to distribute to MacOs or IOs, you will need a Mac or to find an online service to do it;
2. Microsoft Visual Studio: If you want to work with Microsoft computers and mobile (free and pro version);
3. Android: Free if you have time to expend configuring and debugging your favorite IDE as Eclipse or NetBeans.
HERE AND NOW
You can develop simple apps for free, but if you need a professional multi-platform code design, you will have to expend a few hundred dollars in order to have access to all platforms and their peculiarities.