Swift/Kotlin alignment: discard preload cache on configuration changes

[kieran-osgood-shopify]

TLDR

This PR fixes a bug in swifts preload cache invalidation after configuration changes, as well as aligns the implementation otherwise to Kotlins

Details

I observed a fork in behaviour between Swift and Kotlin

Kotlin discards the CheckoutWebView cache on each configuration change (ShopifyCheckoutKit.configure {})
Swift only invalidated after configuration changes if preloading had changed

Thats the divergent behaviour

The bug is that other properties in configuration drive behaviour of preload, not responding to these means the preload is actually stale

• appearance (visual)
• platform (drives user agent)

Approach Rationale

I considered updating the swift side to additionally check for appearance and storefront changes to keep this atomic, however opted to match to kotlins for these reason:

• Documenting this behaviour for consumers is easier: "ShopifyCheckoutKit.configure {} calls / direct mutation via ShopifyCheckoutKit.configuration will always discard preloaded checkouts"
• Avoids stale case bug where we add another property to configuration that preload relies on and isn't keyed on for invalidation

---

Before you merge

Important

• I've added tests to support my implementation
• I have read and agree with the Contribution Guidelines
• I have read and agree with the Code of Conduct
• I've updated the relevant platform README (platforms/swift/README.md and/or platforms/android/README.md)

---

Releasing a new Swift version?

• I have bumped the version in ShopifyCheckoutKit.podspec
• I have bumped the version in platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift
• I have updated the SwiftPM/CocoaPods version snippets in platforms/swift/README.md (major version only)

Releasing a new Embedded Checkout Protocol version?

• I have bumped embeddedCheckoutProtocolAndroid in platforms/android/gradle/libs.versions.toml
• I have updated protocol/languages/kotlin/embedded-checkout-protocol/api/embedded-checkout-protocol.api if the public API changed

Releasing a new Android version?

• I have bumped checkoutKitAndroid in platforms/android/gradle/libs.versions.toml
• I have updated the Gradle/Maven version snippets in platforms/android/README.md

Tip

See the Contributing documentation for the full release process per platform.

[github-actions]

Package Size

Platform	Artifact	Base	Head	Delta
Android	release AAR	291.2 KiB	291.2 KiB	-1 B

Android file breakdown

File	Base	Head	Delta
classes.jar	308.4 KiB	308.4 KiB	+1 B
res/layout/checkout_view_content.xml	2.6 KiB	2.6 KiB	0 B
res/layout/checkout_sheet_content.xml	2.0 KiB	2.0 KiB	0 B
res/values/values.xml	1.3 KiB	1.3 KiB	0 B
R.txt	1.2 KiB	1.2 KiB	0 B
AndroidManifest.xml	922 B	922 B	0 B
proguard.txt	798 B	798 B	0 B
res/drawable/close.xml	431 B	431 B	0 B
res/menu/checkout_menu.xml	354 B	354 B	0 B
META-INF/com/android/build/gradle/aar-metadata.properties	157 B	157 B	0 B

Measured from the PR base SHA and PR head SHA. The file breakdown shows uncompressed sizes within each package artifact, so individual files do not sum to the compressed artifact total. This comment reports package artifact sizes only; it is not a final app binary-size report.

[bitrise]

Install this build

Open Tophat, select your target device, then click Install. Links open on the Mac running Tophat.

SDK	Install
Swift	Install with Tophat
Kotlin	Install with Tophat

Checkout Kit E2E results

Status	Suite	Target	Platform	OS version tag	Device
✅	kotlin-android	kotlin	android	latest	Google Pixel 9 Android 17.0
✅	swift-ios	swift	ios	latest	iPhone 15 iOS 27 Beta

[kieran-osgood-shopify]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Swift/Kotlin alignment: discard preload cache on configuration changes #680 👈 (View in Graphite)
• fix: swiftui modifiers should be instance scoped #681
• main

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