Inter-App Communication framework makes x-callback-url easy

Inter-App Communication, IAC from now on, is a framework that allows your iOS app to communicate, very easily, with other iOS apps installed in the device that supports the x-callback-url protocol. With IAC you can also add an x-callback-url API to your app in a very easy and intuitive way.

Looks very cool. Been thinking about implementing x-callback-url, but haven’t? You might want to check out this library.

A call to iOS Twitter client developers!

With Instapaper’s x-callback-url support available, I hope people will start to see some of the cool possibilities for more complex handoffs between iOS apps. The next big thing I’d really like to see is for Twitter clients to extend their URL schemes to support x-callback-url, particularly to allow the user to jump over to post a tweet, and then be returned to what they were doing in their original app.

Most of the major iOS Twitter clients already support incoming URLs for status updates. For example, if you want to send a status update to Twitteriffic, just call:


For Twitter:


This is strictly a one-way call, however. Why not use x-callback-url to allow passing a return callback for after the user edits and sends the tweet. For example:


NOTE: arguments should be URL encoded, but were not for legibility.

This could work very much like the existing support in the Twitter app, opening the compose window with the text pre-entered — but after the user taps “Send” and the tweet is successfully posted, fire the callback URL and return the user to where they started.

With this sort of support available, it would be easy for apps to add “Share” functionality that lets their user take advantage of the accounts their users already have setup in their Twitter client, along with all the great composing tools, without forcing the user having leave their app with no clear way back.

If you think this is a cool idea, contact the developer of your favorite Twitter client and let them know. And tell them we’d be happy to help with testing!

Instapaper 3.0.2 with x-callback-support now available

Instapaper 3.0.2 has hit the app store. This is the first version of Instapaper to support x-callback-url. Marco Arment, the developer behind Instapaper, was important to the formation of the ideas in x-callback-url, and we’re excited to see this version hit the store.

Instapaper’s integration with Terminology also represents the first “in-the-wild” use of x-callback-url’s two way callback support. If you select to lookup a word in Terminology from Instapaper, you are provided an easy way to jump right back to where your were. See Marco’s post for details.