Preface

Mobile applications ceased to be the "new hotness" a long time ago, and these days users routinely expect that new software—be it a videogame or a social network—has a mobile version. Similar trend affects desktop operating systems; writing cross-platform software, once uncommon, has swiftly become a norm. Even game developers, usually limited to Microsoft operating systems on desktop, can be seen working on Mac and Linux ports for many new titles (for example, Steam, at the time of writing, hosts more than a hundred games that run on Mac and more than 50 that run on Linux).

This is especially valuable for start-ups and indie developers: building truly cross-platform software widens the potential audience, which leads to increased sales and may create good press along the way.

On the downside, writing portable software can be a very resource-hungry process, and this also affects small developers much more than big corporations.

In particular, many platforms have a preferred programming language and software development kit (SDK): iOS apps are mostly written in Objective-C and Swift, Android suggests the subpar Java programming language, and Microsoft promotes the use of the .NET framework, especially C#, for building Windows software.

Employing these tools allows you to leverage the native user interface and underlying functionality of an OS, but it also automatically prevents code reuse. This means that even if you are equally proficient in all programming languages and interfaces involved, porting the code may still take a non-trivial amount of time and introduce new bugs.