Chapter 21. iMessage Stickers and Apps

We all use messaging capabilities on our iOS devices. This is a bold statement and I have no proof for it, but it’s difficult to imagine a person owning an iOS device without having sent or received messages. The main messaging application on iOS is iMessage, but it’s not the only messaging option for iOS. You can download and choose among a huge selection of various messaging applications.

iMessage used to be fully closed. That is to say, it lived in its own sandbox (and still does), and did not allow any extensions to be attached to it. But now that has changed, and we developers can finally write our own iMessage extensions that allow even more interactivity to be added to our conversations.

iMessage apps can be of two different types:

Sticker packs

These are a special, unusual kind of app that contain only images, with absolutely no code. You can create this kind of app so users can send the images to one another in iMessage. For instance, if you offer a sticker pack full of heart shapes, users can then download the app and attach those hearts to messages that they or others send. In other words, as the name implies, images can stick to messages!

Full-fledged apps

With this type of iMessage app, you have full control over how your app works. You can do some really fun stuff, which we will review soon. For instance, you can change an existing sticker that was sent previously by one of your contacts, so that you and the person you’re chatting ...

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