Rendered Objective-C code blocks don't have syntax highlighting

[electricbolt]

Bug description

When editing inside GitBook, Objective-C code blocks are syntax highlighted. The rendered docs on my website though are not syntax highlighted. (Swift, Kotlin, Java, Dart are working great).

How to reproduce

1. View https://docs.electricbolt.co.nz/configuration-subclasses/supported-property-types/integer#slider-ui

No Objective-C syntax highlighting when viewing rendered docs:

But in GitBook editor it's fine:

Additional context