is instantaneous with iVim (GitHub page):
Import text from other apps, iCloud Drive, etc, or simply copy text files via USB / iTunes File Sharing. Once copied, open files via :o filename or browse available files via :e .
While browsing, rename files via R and create new files via %, entering desired filename when prompted.
To enable case insensitive search and open the same file on every launch, create .vimrc and save the following lines:
set ic
autocmd VimEnter * edit filename
Search forward with / and backward with ?.
While searching, use * to find the next instance of the word currently under the cursor, and # to find the previous instance of the same word (n and N can also be used, but are not as convenient to switch between on the iOS keyboard).
Close a file but leave iVim running via :bd (which deletes the buffer).
Sources:
/misc | Jan 08, 2019