Cross platform chanllenges

• The code that needs to be different can be refactored into separate classes. For each runtime, these classes can then be implemented differently while the rest of the code can be shared for all targeted runtimes.  

• In some cases, conditional compilation allows individual lines of code to differ for different runtimes in the same source code file. By defining different conditional compilation symbols for different runtimes, only the correct lines of code will be compiled for each runtime.