How does iOS determine which share extensions are enabled by default?

Question

Some apps have their \'Share Extensions\' enabled by default when installing the app. Flickr is an example of this.

However, other apps do not - OneNote, Wu

Answer 1

These apps have agreements with Apple. If you look at your settings app, you can see these apps that have agreements. Vimeo is another app with a similar agreement. As far as I know, there is no way to set your app to have the share extension enabled by default.

Note that I do not have Vimeo installed, but it's still in the Settings app.