The Lack of this feature for iOS can almost be considered a severe BUG. It totally breaks the work flow used by many users, and advocated in enoumerous articles and post about how to use Evernote. Adding to this, this request has been around from many users since years, by a lot of payed users and there until the moment no single reply from Evernote. Please consider the priority of this.
For previewing notes written in markdown (sort of real time), you can check this post: Evermark Note: currently working for mac osx, but should be possible to port for windows.