Excel Workbook (.xlsx). The default, XML-based workbook format for Excel 2016 for Mac, Excel for Mac 2011, and Excel for Windows. Cannot store VBA macro.

I can teach myself Objective C on the web and set 'write Excel viewer' as my first assignment. As already stated in other answers, you can use Apple's 'Numbers' to open Excel files, but creating or modifying Excel files programatically is a different story; you might need to have the appropriate tools (SDKs etc.) installed to do that. Mac word shortcut for itallics. May I ask what tutorial you're following?

If the guide has prerequisites, it should specify how to meet them. (Depending on what exactly you want to accomplish, this might actually be a question better asked on StackOverflow).