I am looking to insert a special character or symbol into my documents, which are intended to be markdown formatted text files. The symbol is intended to be used to represent a tick box or other tick/cross visual symbol (either empty, or actually ticked). Examples provided below (inserted using Edit > Special Characters in Safari)
Once I have used it in a file, I want the symbol to be readable regardless of whether I view the file through an app in either OS X or iOS, as well as capable of being inserted from any source including the iPhone keyboard
What is the best method of ensuring consistent input and viewing of such characters works across the board, is there a particular font family or Unicode code that will enable portability across my devices, and is there a simple way to insert them, possibly via text expander or autocorrect if they are not on the main keyboard?