Textastic uses the Oniguruma regex engine like TextMate.

Here's how Textastic checks whether it needs to display code completions:

• First, it looks if the scope at the cursor matches the scope selector of a code completion context (this is the "scope" element in a context) - you can show the current scope in Textastic by tapping in the editor with three fingers. It's probably easier to use TextMate on a Mac though.
  
• If the scope selector matches, Textastic tries to match the regular expression in the "pattern" backwards from the cursor position
• If the regular expression matches, it will uses the capture defined by the "completionCaptureIndex" as a prefix for the strings referenced by the "completionSetNames" array
• It will show all strings from the completionSet that have the prefix found in the previous step

No, sorry, I think editing binary files is out of the scope of a text editor.

I would recommend renaming it to yourfile.plist afterwards in order to get proper syntax highlighting.

I see. Your file is not a text file, but a binary plist file. You need to convert it to XML format to be able to edit it in a text editor like Textastic. You can do that on the command line on your Mac:

plutil -convert xml1 yourfile.strings

Did you try to tap on it? What happened?

Which encoding does the file have? .strings file are often UTF-16 files. Maybe your file doesn't have a proper Byte Order Mark (BOM). You could try to tap-and-hold the file, choose "Open with Encoding" and select UTF-16. Does that work?

Binary files are greyed out. You can tap on it anyway and try to open it, but if it is not a proper text file, it probably won't open.

What you can do is the following:

- Download the site to a folder

- Create a copy of that folder which serves as your backup

The iPhone version of Textastic is available on the App Store: https://itunes.apple.com/us/app/textastic-code-editor-for-iphone/id550156166?mt=8

You can find the website with screenshots of the iPhone version of Textastic at http://www.textasticapp.com/iphone.html

There is also an updated manual available at http://www.textasticapp.com/iphone/manual/

This will be fixed in the next update