[webview_flutter_wkwebview] Tear down ProxyAPIRegistrar in applicationWillTerminate

[bparrishMines]

InstanceManager contains the only strong reference to the finalizer delegate that makes the call to Dart when an object is deallocated. This sets the plugin to listen for applicationWillTerminate to tear down the ProxyAPIRegistrar.

Potential fix for flutter/flutter#168535 . This crash is difficult to reproduce, so this is just a attempt to prevent it because most of the stacktraces in the issue include [UIApplication _terminateWithStatus:]. It's possible this could clean up the plugin before the crash can happen.

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[gemini-code-assist]

Code Review

This pull request updates the webview_flutter_wkwebview plugin to tear down the proxyApiRegistrar when the application terminates on iOS, preventing message calls during shutdown. The changes include a version bump to 3.24.4, updates to the Xcode project file, and the addition of a lifecycle test. Review feedback identifies a potential crash from force-unwrapping in the teardown method, a missing file reference in the project configuration causing build failures, and a memory leak in the test suite.

[gemini-code-assist]

The proxyApiRegistrar is an optional that is set to nil at the end of this method. Since tearDownProxyAPIRegistrar is now called from both detachFromEngine and applicationWillTerminate, it is possible for it to be called twice during application shutdown (for example, if the engine is detached and then the application terminates). The force-unwrapping of proxyApiRegistrar will cause a crash on the second call. It should be handled safely using a guard or optional chaining.

  private func tearDownProxyAPIRegistrar() {
    guard let registrar = proxyApiRegistrar else {
      return
    }
    registrar.ignoreCallsToDart = true
    registrar.tearDown()
    proxyApiRegistrar = nil
  }

[gemini-code-assist]

The project file references PlatformViewImplTests.swift (also seen on lines 133, 181, and 508), but this file is not included in the pull request. This will cause a build failure in the example app's test target as the compiler will be unable to find the file.

[gemini-code-assist]

Using malloc(1) as a key for objc_setAssociatedObject results in a memory leak because the allocated memory is never freed. While this is a test, it is better practice to use the address of a static or local variable as a unique key to avoid manual memory management issues.