There is now a basic syntax definition for Swift available for Textastic:

This is a repackaged version of the Sublime Text package for the Swift programming language that you can find at github.com/quiqueg/Swift-Sublime-Package.

Installation

Instructions for the iPad and iPhone version of Textastic:

• Create a folder called #Textastic under Local Files if it doesn't exist. If it is named correctly, it will have a special folder icon with a gear symbol.
• Open this link in Safari on your iOS device: http://www.textasticapp.com/support/Swift.tmbundle.zip
• Select "Open In" and choose "Open in Textastic".
• When Textastic asks if you want to unpack the file Swift.tmbundle.zip, select Yes.
• There should now be a folder Swift.tmbundle under Local Files. If you can't see this folder, pull the file listing down to refresh it.
• Move the folder Swift.tmbundle to the #Textastic folder you created above. You can do this with the "Edit" button - see How can I move, copy and rename files and folders?
• Restart Textastic.
• After you start the app, the Swift syntax definition can be chosen in the File Properties popover. It will be used automatically for .swift files.

Congratulations! You can now view Apple's Swift sample code right on your iOS device.

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For more detailed installation information with screenshots, please have a look at the installation instructions in Textastic's manual:

• for iPad
• for iPhone
• for Mac

Screenshot

Hello,

sorry, but this is not supported. Among other things, Textastic requires AutoSave to work properly with iCloud. 

What you can do, is enable this setting in System Preferences -> General:



This will ask you if you want to keep your changes when you close a file and allow you to revert the changes.

What kind of file is that in your case? As far as I know, .conf files can be in a lot of different formats depending on the application that uses it. You can just select the appropriate syntax definition from the File Properties menu and Textastic will use it for all files with the same file extension.

Textastic offers syntax highlighting for many languages including PHP, but it doesn't include compilers or interpreters due to restrictions of iOS.If you try to preview the php file locally, only the html part will be interpreted by the web view. The PHP part will be ignored.

In order to preview PHP in Textastic, you can upload the file to a test server, open the preview screen, switch from "Local" to "Remote" and enter the remote url of your test server.

You will notice that all apps that support running code - like Kodiak, Codea and Pythonista for example - do not have file download capabilities. So, if I wanted to add the ability to run code in Textastic, I'd have to remove FTP, "Open In", WebDAV, Dropbox and all other means of sharing files with other apps.


This is what the iOS Developer Program License Agreement says:

3.3.2 An Application may not download or install executable code. Interpreted code may only be used in an Application if all scripts, code and interpreters are packaged in the Application and not downloaded. The only exception to the foregoing is scripts and code downloaded and run by Apple's built- in WebKit framework, provided that such scripts and code do not change the primary purpose of the Application by providing features or functionality that are inconsistent with the intended and advertised purpose of the Application as submitted to the App Store. 


These are the relevant points in the App Store review guidelines:

2.7 Apps that download code in any way or form will be rejected
2.8 Apps that install or launch other executable code will be rejected

Textastic offers syntax highlighting for many languages including C, C++, and Python, but it doesn't include compilers or interpreters due to restrictions of iOS.