[webview_flutter_wkwebview] Add webkit interface for showing javascript alert message

[jsharp83]

• In the iOS Webview environment, there are cases where Web calls System Popup with javascript.
• At this time, the message comes in the WKUIDelegate part.
  • https://developer.apple.com/documentation/webkit/wkuidelegate/1537406-webview
  • https://developer.apple.com/documentation/webkit/wkuidelegate/1536489-webview
• It was implemented according to the requirements of the code review of the previous PR.
• Related issue: alert() method doesn't work in WebView flutter#30358 (comment)

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[bparrishMines]

@jsharp83 Thanks for the contribution! It looks like this feature is also supported on Android, onJSAlert, so we should add support for this in the common platform interface: webview_flutter_platform_interface.

See https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#changing-federated-plugins for more info on the process of doing this.

[jsharp83]

@bparrishMines Thanks for the review.

Unlike iOS, in Android, System popup works without any additional implementation. I added a test code on webview_flutter_android example, so you can check it .

Even Android supports system popup in Javascript, someone wants to use flutter version of alert. If you think that it is necessary things to support, I will additionally implement it on android platform.

Thanks.

[jsharp83]

@bparrishMines I checked onJsAlert, onJsConfirm and onJsPrompt function in WebChromeClient you already mentioned. I will implement a interface with it on WebChromeClientHostApiImpl.java

[bparrishMines]

@jsharp83 Yea, I think we should still add a common platform interface for this method since it is supported on Android. The reason being that someone could want to override the default JS alerts on Android and we don't want to create an interface on iOS that is difficult for Android to implement at a later date.

[niumj]

@jsharp83
Add webkit interface for showing javascript alert message

Thank you for your contents. But when I add the changes to [webview_flutter_wkwebview] , the below errors
FWFWKJavaScriptPanelType Expected a type
Unknown type name 'FWFWKJavaScriptPanelCompletionData'
Use of undeclared identifier 'FWFWKJavaScriptPanel'

FWFWKJavaScriptPanelCompletionData Expected ')'

What can I do? or can you upload other neccessary files?

[jsharp83]

@niumj

It is defined in
packages/webview_flutter/webview_flutter_wkwebview/pigeons/web_kit.dart

You should run pigeon script on webview_flutter_wkwebview folder

flutter pub run pigeon --input pigeons/web_kit.dart

I closed this PR because I uploaded a new PR with Android version implementation.

If you just add a feature temporary in iOS, check this commit
main...jsharp83:packages:temp-add-javascript-system-popup

[niumj]

@jsharp83
Thank you for your attention.
But when I use it, system popup is working, the below error is also happened.

• [[FWFUIDelegate webView:runJavaScriptConfirmPanelWithMessage:initiatedByFrame:completionHandler:] was called more than once']

After that the app is exited.
How can I do or any suggestions?