Files on iOS that are located outside of Texifier may be opened in Texifier either through the Open in menu most maps have, or through the file storages system.

All applications on iOS must declare to iOS the file types they can open. All applications on the list for a filetype will be shown in the Open in menu for a file. Please note that neither Texifier, nor any other application, declares those file types which it should open, the choice is always up to the user.

There have been instances where some applications are affected by Texifier declaring that it can access a specific filetype. This is not a bug with Texifier, as mentioned above Texifier declares those files it can open and interact with if a user should choose to do so. It does not specify that it should open it, or that any other application should behave differently because Texifier is capable of editing that filetype.

You would need to contact the vendor of the application that is affected to resolve the problem.