Conditional compilation should not be used

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 
#else 
    let a = 3 
#endif