The iPad/iPhone app Quine makes it possible to edit and save changes to TiddlyWiki5, including working offline without a network connection. Download it here.
Instructions for use:
Open Quine
On iPad
Touch the file button (<) or swipe from the left of the screen to open the file list
On iPhone
The file list will show automatically unless a wiki is already open
Touch the new file button (+) in the file list window to create a new TiddlyWiki5 file
Swipe any file item from the right to see a list of additional "actions" possible for that file
Touch any listed file item or folder to open it - wikis will open in Quine's custom browser