Digital stickers for iMessage have been around for a few years now. If you are a digital artist creating assets for printables, note-taking apps and other projects, you probably have assembled many sticker packs or pages. Have you considered repurposing these digital stickers for iMessage? All you need is Xcode and an Apple Developer account ($99/yr).

As your customer can include your stickers within their message text, you will want to create them as PNGs with a transparent background. Besides adding the stickers within the text, stickers can be put on top of speech bubbles, other stickers and photos. For example, one person can send a sticker with a message and the recipient can add more stickers to the original and send it back.

As an animator and a fan of Apple Motion, I'm glad that the iOS stickers can be animated and you don't even need to know how to code. You can submit an animated GIF, animated APNG and an image sequence. Xcode will automatically convert your image sequence in to a single animated file.

Unlike digital and printable stickers that can be sold on various marketplaces such as Creative Market, you will sell your iMessage stickers on the App Store for iMessage. Your customers can assess the App Store and purchase/download your stickers from within the Messages app. As with any marketplace, the sticker category is a bit saturated. But you've already created the images for another purpose and it doesn't take much time to package the images as a sticker app.

Besides the sticker images, you will also need the basic graphics for an iOS app, including the App Icon and Screenshots. If you're selling your app for the iPhone and iPad, you will need screenshots for both. One nice feature that they didn't have when I made my book apps years ago is the App Preview. You can record the functionality of your sticker app using the QuickTime Player, iMovie and Final Cut Pro. Again you will need a preview for both iPhone and iPad.

Submitting your stickers pack app to the App Store doesn't require coding either. Just fill in the new project form in Xcode. You have options as to how your app will be listed in the App Store.

Sticker Pack App and Sticker Pack Extension - Listed in the Stickers category, basic sticker pack of still and animated images. No other functionality.

iMessage App and iMessage App Extension - Listed in the Stickers or another category relevant to the purpose of your app. This app can include stickers, text, video and audio. You will need to use code to add functionality.

For inspiration, I usually start with a Google search and click on Images. This search will give me a broad list of links to Pinterest and other sites.

Building Sticker Packs
https://developer.apple.com/videos/play/tutorials/building-sticker-packs/

Creating Stickers with Motion
https://developer.apple.com/support/stickers/motion/

Preparing Sticker Submissions
https://developer.apple.com/app-store/sticker-submissions/

iMessage Apps
https://developer.apple.com/imessage/

Preparing Your iMessage App for Submission
https://developer.apple.com/app-store/imessage-app-submissions/

App Store Connect Help
https://help.apple.com/app-store-connect/

Show More with App Previews
https://developer.apple.com/app-store/app-previews/

Creating Videos for App Previews
https://developer.apple.com/support/app-previews/