If you post a sample of the text, we can probably give you a better answer (not clear what you're asking), but this sounds like a perfect candidate for core data or sqlite. Once you have the text separated by date/text combos, it becomes pretty simple to do a search by the appropriate date, and show only the relevant text.
By the way, having it in a *.doc format is just going to add unnecessary overhead. If you really want to have it in a flat file, use something like json.