feat: Implement App-Bound Domains to enable Service Workers in WKWebView on iOS14+

Feature Request

Description

Since iOS14, it’s possible to make service workers works in WKWebView by providing a list of trusted domains (up to 10). These domains then gain support for service workers, which is invaluable for us as we plan to use server.url in production to distribute our PWA on iOS.

Here are links describing the possibilities and features :

• https://firt.dev/ios-14/#service-workers
• https://webkit.org/blog/10882/app-bound-domains/

Platform(s)

• iOS

Preferred Solution

I think being able to pass the domain list with capacitor’s config file would be enough. Then capacitor could patch the Info.plist file with the domains, and build the WKWebView using the snippet provided in the first post I shared above :

let configuration = WKWebViewConfiguration()
configuration.limitsNavigationsToAppBoundDomains = true
// Create a WebView with this configuration

Alternatives

As of today I don’t think there is any alternative to support service workers in WKWebView

Additional Context

[thomasvidas]

FYI, Ian no longer works at Ionic so he probably won’t answer 😄. To answer your question, here’s why we do not advise using a live server.url:

• Capacitor apps lose the secure context for several web apis. In the config docs we list a few if you scroll down to the server.url option.
• Apple has rejected apps that point to a live URL. Apple’s (and Google’s) app review process is pretty opaque so it’s hard to know exactly why they may reject one app that does this and approve another app. But in general, Apple is pretty clear that if your application is just an existing version of a website bundled in an app, they may reject it.
• It is bad UX to point to an external server since if a user does not have internet access there is no functionality. By pointing to a localhost, the files are on the device. Meaning that even if your user has no internet access, the app is still functional.

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