Long story, but I'm building a site with social icons in my menu bar (as menu items). I'd like them to open respectively on the device's app when clicked on (for example Facebook app on iOS). Problem is, is that my theme isn't allowing me to save menu items with links starting with anything other than http or https.
Where and how can I allow this feature in the theme's file or wherever it is?
It's not your theme that's preventing menu items from being saved with fb: protocol. It's WP Core. WP Menu items are intended to be web URLs, because visitors can typically access a WP site from any device - not just a mobile device. Even a mobile device that doesn't have the Facebook app installed would not recognize a fb: link.
My suggestion would be to create a menu through your theme through some other means - not a WP Menu, but programmatically or even hard-coded, depending on your site's needs.
