I develop a RSS reader App named "iRead", What cloud I do to make open the the RSS Link by launching my App when I open a RSS Link in Safari for iOS，and Safari App recognizes it is a RSS Link. The Condition now is that Safari warn "Can't open the page, this is a RSS Feed Link...
As far as i know you can't. iOS is not Android, where you can select the default app to open something. You can create a Share Extension, so when the user selects to share the RSS Link URL, your app handle the link.