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Every first launch of Textastic. iPhone SE. Latest iOS/Textastic Beta
I think Textastic already has built-in Sublime Text Symbol Definition for sublime-syntax files from PackageDev, but it is based on YAML and works correctly unlike Json-based files
It's custom syntax from Sublime Text PackageDev repo. All json-based files like sublime-color-scheme, sublime-completions,
sublime-menu etc, have a black-colored braces, commas and some comment lines.
If you insert whitespace characters after them (see gif), they are highlighted correctly.
For example, for sublime-color-scheme, you can choose to define the sublime text color scheme syntax
Please keep an eye at some json-based syntaxes from PackageDev
Strange things with curly braces and commas.

You Rock!
Sent! But i have this bug with 'built-in' css.json

At this moment you try MagicPython with custom tmBundle.
Great news, can wait for new betas or release!
Will Textastic for iOS supports new syntax highlighter?
Customer support service by UserEcho
Quickly new beta! Yes problem is gone!