What I'm running on?

Building apps for multiple operating systems from the very same source code imposes unique challenges. Your code might be running on iOS or Android. It only takes two mouse clicks to recompile your app for a different target. Certain features might exist on a given platform and not be there on other platforms. Going further, new functionality is constantly being added to platforms, so we may want to know on which platform and operating system version your app is being executed.

This can be done with the TOSVersion record type defined in the System.SysUtils unit. It has a class constructor that instantiates all its fields. The TOSVersion record type has inner TArchitecture and TPlatform enumerated types and corresponding public class properties to read the current operating system architecture, platform, name, and major and minor numbers. Additionally, we can check major and minor numbers of the service pack level.

We can very quickly build a simple app that will log into...