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Currently that's not possible. Only the buit-in monospaced fonts are available.
13 years ago
Textastic uses functionality in iOS and some additional heuristics to detect the encoding of text files you try to open.
Which character encoding do you use in your files?
I generally recommend using standard Unicode encodings like UTF-8, UTF-16 or UTF-32. These should be detected correctly and also display Chinese characters correctly.
If you use other encodings that can't be detected automatically, you'll have to select the encoding manually by tapping-and-holding a file and choosing "Open with Encoding" the first time you open the file. The second time, the app will remember the chosen encoding.
Textastic already has support for C#. You can try to use the ASP (VB.net) syntax definition for VB.
Textastic 4.0 adds Firebug Lite integration.
Textastic 4.0 will support multiline tabbing and untabbing using the virtual keyboard and external keyboards (select text and press tab and shift-tab).
Textastic 4.0 will support regular expression find and replace.
Textastic 4.0 will have remote preview support.
Textastic 4.0 will have a new row of additional keys that allows you to enter all available special characters by swiping over them. This eliminates the need for configurable buttons.
Textastic 4.0 will have code completion for HTML, CSS and for PHP functions.
This is the new preview screen. It allows you to enter a local path to preview for each file. So, for example, if you want to preview changes to a JavaScript or CSS file, you can enter the path of a HTML file that uses it.
You can also enter a remote url so you don't need to switch to Safari.

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