On the Mac, I can easily set the default app for opening certain types of files. I cannot find this feature in iOS. I want to open markdown files in Drafts but they are opening in iA Writer on my iPad.
Is there a way to change this behavior on the iPhone/iPad?
There is a sort of way to change file associations on iOS but it’s not obvious. For example, if you use the share sheet to share an .md file to iA Writer or Textastic from the Files app, the chosen app becomes the default for that extension. It works with those two apps, just tried that.
However this does not always work reliably; just tried sharing an .md file to Drafts and it did not become the default app for .md files but instead imported the file into a note. 
I guess this has to do with Drafts not working with the filesystem (iCloud Drive) directly but using CloudKit and its own database.
Yeah, was going to reply with the same thing and agreed with your reasoning about why Drafts isn’t working.
Thanks for the tips. I learned something and I am encouraged that it’s not “just me.“ 