DispatchQueue with Background QoS has long delay

[nnnlog]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

In the iOS, first-time loaded page is very slow to complete load(generally DOMContentLoaded).

flutter_inappwebview/flutter_inappwebview_ios/ios/Classes/InAppWebView/WebViewChannelDelegate.swift

Lines 993 to 1010 in 226ebc5

	public func onReceivedServerTrustAuthRequest(challenge: ServerTrustChallenge, callback: ReceivedServerTrustAuthRequestCallback) {
	if channel == nil {
	callback.defaultBehaviour(nil)
	return
	}
	// workaround for ProtectionSpace.toMap() SSL Certificate
	// https://github.com/pichillilorenzo/flutter_inappwebview/issues/1678
	DispatchQueue.global(qos: .background).async {
	let arguments = challenge.toMap()
	DispatchQueue.main.async { [weak self] in
	if self?.channel == nil {
	callback.defaultBehaviour(nil)
	return
	}
	self?.channel?.invokeMethod("onReceivedServerTrustAuthRequest", arguments: arguments, callback: callback)
	}
	}
	}

It seems like to DispatchQueue with Background QoS has long delay. I just printed log in Line 998 (before queue), and Line 1003 (in queue). In some cases, the time between the two logs being output was as long as one minute.

Expected Behavior

It should be execute (almost) immediately, still not affecting main thread.

Steps with code example to reproduce

It is very difficult to reproduce issue but it occurs explicitly.

1. Prepare the device with cleaned iOS. (In Simulator, you can reproduce this behavior with Device -> Erase all content ...)
2. Load any page with HeadlessInAppWebView. (I don't verify that this issue can be produced by general webview instance)
3. In first loading, there is too many times to load page including assets such as css/js/image, etc.

Stacktrace/Logs

There is no stacktrace, but attach some logs for debugging.

WebView Console (Safari Technology Preview)

Flutter version

v3.26.0-0.1.pre

Operating System, Device-specific and/or Tool

iOS 18

Plugin version

v6.1.4

Additional information

I have commit (nnnlog@6a0c192) already. I write this issue for opening PR.

Self grab

• I'm ready to work on this issue!

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