Ulysses for Mac, iPad, and iPhone has some powerful search and tagging features. Whether you’re building a body of work for a publication, writing a book, freelancing, or just about any other kind of writing, it’s easy to organize all your content with Groups (folders) and Keywords (tags).
One perk I recently discovered in the Mac version is the option to search in the current Group (Edit > Find > Search in Group or Command + Shift + F). Once you trigger this feature, a search box will appear at the top of the list of sheets (notes, documents, etc.). Click the keyword icon next to the search box, and a second section will appear containing the keywords used in the current Group.
Click a keyword, and sheets in the current Group will filter for it. Select the menu option again, or use the keyboard shortcut, to dismiss the search and Keyword filter options.