pebble/devsite/source/_guides/migration/migration-guide-4.md

title	description	permalink	generate_toc	guide_group	order
SDK 4.x Migration Guide	Migrating Pebble apps from SDK 3.x to SDK 4.x.	/guides/migration/migration-guide-4/	true	migration	4

This guide provides details of the changes to existing APIs in Pebble SDK 4.x. To migrate an older app's code successfully from Pebble SDK 3.x to Pebble SDK 4.x, consider the information outlined here and make the necessary changes if the app uses a changed API.

The number of breaking changes in SDK 4.x for existing apps has been minimized as much as possible. This means that:

• Apps built with SDK 3.x will continue to run on firmware 4.x without any recompilation needed.

• Apps built with SDK 4.x will generate a .pbw file that will run on firmware 4.x.

New APIs

• AppExitReason - API for the application to notify the system of the reason it will exit.
• App Glance - API for the application to modify its glance.
• UnobstructedArea - Detect changes to the available screen real-estate based on obstructions.

Timeline Quick View

Although technically not a breaking change, the timeline quick view feature will appear overlayed on a watchface which may impact the visual appearance and functionality of a watchface. Developers should read the {% guide_link user-interfaces/unobstructed-area "UnobstructedArea guide%} to learn how to adapt their watchface to handle obstructions.

appinfo.json

Since the introduction of Pebble Packages in June 2016, the appinfo.json file has been deprecated and replaced with package.json. Your project can automatically be converted when you run pebble convert-project inside your project folder.

You can read more about the package.json file in the {% guide_link tools-and-resources/app-metadata "App Metadata" %} guide.

Launcher Icon

The new launcher in 4.0 allows developers to provide a custom icon for their watchapps and watchfaces.

{% markdown %}  {% endmarkdown %}

{% markdown %}  {% endmarkdown %}

If your png file is color, we will use the luminance of the image to add some subtle gray when rendering it in the launcher, rather than just black and white. Transparency will be preserved.

You should add a 25x25 png to the resources.media section of the package.json file, and set "menuIcon": true. Please note that icons that are larger will be ignored and your app will have the default icon instead.

"resources": {
  "media": [
    {
      "menuIcon": true,
      "type": "png",
      "name": "IMAGE_MENU_ICON",
      "file": "images/icon.png"
    }
  ]
}