Conditional compilation is generally recognized as a bad practice that is occasionally necessary when dealing with platform-specific code. As much
as possible, code should be refactored to minimize or eliminate conditionally-compiled, platform-specific code because even when necessary and
well-intentioned, such code segments can leave your codebase in a hopeless tangle.
Noncompliant Code Example
#if os(OSX) // Noncompliant
let a = 2
let a = 3