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Activity items and share extensions

I'm not 100% sure this is all accurate but:

It seems as though share extension predicates are a lot more specific than we originally thought. For example, if Instapaper declares support for only NSExtensionActivationSupportsWebURLWithMaxCount = 1, this means that activity controllers configured with a URL but also some other item types too, e.g. a string, won't show Instapaper.

So basically if you have multiple items in your activity items array, your controller will only show extensions that support all types. I imagine this would be extremely limiting, and as such, think the best option is to:

  • Only include a single provider in your items array. The provider would have a placeholder of a single type that will be provided to any activity or extension that isn't specifically accounted for
  • In the provider, specifically hardcode alternative item types for activities that need an alternative to the placeholder type:
    • "Copy" activity could use photo data, if present
    • "Mail" activity would get a string to use as the message body

This sucks because we're limiting how useful sharing from our app is if we only export a single data type. But I'm not sure that there's a way to be any more accomodating.

Donohue commented Sep 5, 2014

Alternatively, your share extension's NSExtensionActivationRule must include NSExtensionActivationSupportsText in addition to NSExtensionActivationSupportsWebURLWithMaxCount

h/t https://github.com/blork/

blork commented Sep 5, 2014

This is the behaviour I'm seeing (https://devforums.apple.com/message/1012526), and it seems very counterintuitive.

The way around it is for the extension developer to be super lenient about what they can be passed, which is what I'm having to do for now. It doesn't really work when you start to think about sharing both an image and a URL though, since the apps that can handle one will probably not be equipped to handle the other.

Edit: As @donahue says, for extensions that need to operate on a URL/webpage it seems best to set NSExtensionActivationSupportsText, NSExtensionActivationSupportsWebURLWithMaxCount=1 and NSExtensionActivationSupportsWebPageWithMaxCount=1, and deal with them something like this: https://gist.github.com/blork/3908619597ab4515941d

Donohue commented Sep 5, 2014

Also FWIW, I can get a website from Safari via kUTTypePropertyList without NSExtensionActivationSupportsWebPageWithMaxCount, and NSExtensionActivationSupportsWebURLWithMaxCount must be at least 1. See:

https://devforums.apple.com/message/1014247#1014247

Interesting… I'm hoping that we end up with extensions that are a little more lenient about what types of activity items they accept. I'm currently finishing up a feature that shares an image, string description, and a URL, and was aiming for compatibility with apps like Instagram, Tumblr, and Pinterest (if they offer extensions). I was originally using three activity items, but after reading this I've changed it to just an image and a string (with the URL as part of the string).

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