Ensure that the dom is fully loaded on *all* web views before being made available to process JavaScript. Issue #1756 & Issue #1808

NetNewsWire.xcodeproj/project.pbxproj

@@ -246,6 +246,7 @@
 		51D87EE12311D34700E63F03 /* ActivityType.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51D87EE02311D34700E63F03 /* ActivityType.swift */; };
 		51DC37072402153E0095D371 /* UpdateSelectionOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51DC37062402153E0095D371 /* UpdateSelectionOperation.swift */; };
 		51DC37092402F1470095D371 /* MasterFeedDataSourceOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51DC37082402F1470095D371 /* MasterFeedDataSourceOperation.swift */; };
+		51DC370B2405BC9A0095D371 /* PreloadedWebView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51DC370A2405BC9A0095D371 /* PreloadedWebView.swift */; };
 		51E36E71239D6610006F47A5 /* AddWebFeedSelectFolderTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51E36E70239D6610006F47A5 /* AddWebFeedSelectFolderTableViewCell.swift */; };
 		51E36E8C239D6765006F47A5 /* AddWebFeedSelectFolderTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = 51E36E8B239D6765006F47A5 /* AddWebFeedSelectFolderTableViewCell.xib */; };
 		51E3EB33229AB02C00645299 /* ErrorHandler.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51E3EB32229AB02C00645299 /* ErrorHandler.swift */; };
@@ -1383,6 +1384,7 @@
 		51D87EE02311D34700E63F03 /* ActivityType.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ActivityType.swift; sourceTree = "<group>"; };
 		51DC37062402153E0095D371 /* UpdateSelectionOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UpdateSelectionOperation.swift; sourceTree = "<group>"; };
 		51DC37082402F1470095D371 /* MasterFeedDataSourceOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MasterFeedDataSourceOperation.swift; sourceTree = "<group>"; };
+		51DC370A2405BC9A0095D371 /* PreloadedWebView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PreloadedWebView.swift; sourceTree = "<group>"; };
 		51E36E70239D6610006F47A5 /* AddWebFeedSelectFolderTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AddWebFeedSelectFolderTableViewCell.swift; sourceTree = "<group>"; };
 		51E36E8B239D6765006F47A5 /* AddWebFeedSelectFolderTableViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = AddWebFeedSelectFolderTableViewCell.xib; sourceTree = "<group>"; };
 		51E3EB32229AB02C00645299 /* ErrorHandler.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ErrorHandler.swift; sourceTree = "<group>"; };
@@ -2015,6 +2017,7 @@
 				518651D9235621840078E021 /* ImageTransition.swift */,
 				5142192923522B5500E07E2C /* ImageViewController.swift */,
 				512D554323C804DE0023FFFA /* OpenInSafariActivity.swift */,
+				51DC370A2405BC9A0095D371 /* PreloadedWebView.swift */,
 				51AB8AB223B7F4C6008F147D /* WebViewController.swift */,
 				517630222336657E00E15FFF /* WebViewProvider.swift */,
 				51C9DE5723EA2EF4003D5A6D /* WrapperScriptMessageHandler.swift */,
@@ -4009,6 +4012,7 @@
 				51627A6923861DED007B3B4B /* MasterFeedViewController+Drop.swift in Sources */,
 				514219372352510100E07E2C /* ImageScrollView.swift in Sources */,
 				516AE9B32371C372007DEEAA /* MasterFeedTableViewSectionHeaderLayout.swift in Sources */,
+				51DC370B2405BC9A0095D371 /* PreloadedWebView.swift in Sources */,
 				C5A6ED5223C9AF4300AB6BE2 /* TitleActivityItemSource.swift in Sources */,
 				51DC37092402F1470095D371 /* MasterFeedDataSourceOperation.swift in Sources */,
 				51C4529B22650A1000C03939 /* FaviconDownloader.swift in Sources */,

iOS/Article/PreloadedWebView.swift

@@ -0,0 +1,81 @@
+//
+//  PreloadedWebView.swift
+//  NetNewsWire-iOS
+//
+//  Created by Maurice Parker on 2/25/20.
+//  Copyright © 2020 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+import WebKit
+
+class PreloadedWebView: WKWebView {
+	
+	private struct MessageName {
+		static let domContentLoaded = "domContentLoaded"
+	}
+	
+	private var isReady: Bool = false
+	private var readyCompletion: ((PreloadedWebView) -> Void)?
+	
+	init(articleIconSchemeHandler: ArticleIconSchemeHandler) {
+		let preferences = WKPreferences()
+		preferences.javaScriptCanOpenWindowsAutomatically = false
+		preferences.javaScriptEnabled = true
+
+		let configuration = WKWebViewConfiguration()
+		configuration.preferences = preferences
+		configuration.setValue(true, forKey: "allowUniversalAccessFromFileURLs")
+		configuration.allowsInlineMediaPlayback = true
+		configuration.mediaTypesRequiringUserActionForPlayback = .video
+		configuration.setURLSchemeHandler(articleIconSchemeHandler, forURLScheme: ArticleRenderer.imageIconScheme)
+		
+		super.init(frame: .zero, configuration: configuration)
+	}
+	
+	required init?(coder: NSCoder) {
+		super.init(coder: coder)
+	}
+	
+	func preload() {
+		configuration.userContentController.add(WrapperScriptMessageHandler(self), name: MessageName.domContentLoaded)
+		loadFileURL(ArticleRenderer.page.url, allowingReadAccessTo: ArticleRenderer.page.baseURL)
+	}
+	
+	func ready(completion: @escaping (PreloadedWebView) -> Void) {
+		if isReady {
+			completeRequest(completion: completion)
+		} else {
+			readyCompletion = completion
+		}
+	}
+	
+}
+
+// MARK: WKScriptMessageHandler
+
+extension PreloadedWebView: WKScriptMessageHandler {
+
+	func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
+		if message.name == MessageName.domContentLoaded {
+			isReady = true
+			if let completion = readyCompletion {
+				completeRequest(completion: completion)
+				readyCompletion = nil
+			}
+		}
+	}
+	
+}
+
+// MARK: Private
+
+private extension PreloadedWebView {
+	
+	func completeRequest(completion: @escaping (PreloadedWebView) -> Void) {
+		isReady = false
+		configuration.userContentController.removeScriptMessageHandler(forName: MessageName.domContentLoaded)
+		completion(self)
+	}
+	
+}

iOS/Article/WebViewController.swift

@@ -29,8 +29,8 @@ class WebViewController: UIViewController {
 	private var topShowBarsViewConstraint: NSLayoutConstraint!
 	private var bottomShowBarsViewConstraint: NSLayoutConstraint!
 	
-	private var webView: WKWebView? {
+	private var webView: PreloadedWebView? {
-		return view.subviews[0] as? WKWebView
+		return view.subviews[0] as? PreloadedWebView
 	}
 	
 	private lazy var contextMenuInteraction = UIContextMenuInteraction(delegate: self)
@@ -450,7 +450,7 @@ private extension WebViewController {
 		
 	}
 
-	func recycleWebView(_ webView: WKWebView?) {
+	func recycleWebView(_ webView: PreloadedWebView?) {
 		guard let webView = webView else { return }
 		
 		webView.removeFromSuperview()
@@ -467,7 +467,7 @@ private extension WebViewController {
 		coordinator.webViewProvider.enqueueWebView(webView)
 	}
 
-	func renderPage(_ webView: WKWebView?) {
+	func renderPage(_ webView: PreloadedWebView?) {
 		guard let webView = webView else { return }
 		 
 		let style = ArticleStylesManager.shared.currentStyle

iOS/Article/WebViewProvider.swift

@@ -11,21 +11,14 @@ import WebKit
 
 /// WKWebView has an awful behavior of a flash to white on first load when in dark mode.
 /// Keep a queue of WebViews where we've already done a trivial load so that by the time we need them in the UI, they're past the flash-to-shite part of their lifecycle.
-class WebViewProvider: NSObject, WKNavigationDelegate {
+class WebViewProvider: NSObject {
 	
-	private struct MessageName {
-		static let domContentLoaded = "domContentLoaded"
-	}
-
 	let articleIconSchemeHandler: ArticleIconSchemeHandler
 	
 	private let minimumQueueDepth = 3
 	private let maximumQueueDepth = 6
 	private var queue = UIView()
 	
-	private var waitingForFirstLoad = true
-	private var waitingCompletionHandler: ((WKWebView) -> ())?
-
 	init(coordinator: SceneCoordinator, viewController: UIViewController) {
 		articleIconSchemeHandler = ArticleIconSchemeHandler(coordinator: coordinator)
 		super.init()
@@ -47,104 +40,39 @@ class WebViewProvider: NSObject, WKNavigationDelegate {
 
 	func flushQueue() {
 		queue.subviews.forEach { $0.removeFromSuperview() }
-		waitingForFirstLoad = true
 	}
 
 	func replenishQueueIfNeeded() {
 		while queue.subviews.count < minimumQueueDepth {
-			let webView = WKWebView(frame: .zero, configuration: buildConfiguration())
+			enqueueWebView(PreloadedWebView(articleIconSchemeHandler: articleIconSchemeHandler))
-			enqueueWebView(webView)
 		}
 	}
 	
-	func dequeueWebView(completion: @escaping (WKWebView) -> ()) {
+	func dequeueWebView(completion: @escaping (PreloadedWebView) -> ()) {
-		if waitingForFirstLoad {
+		if let webView = queue.subviews.last as? PreloadedWebView {
-			waitingCompletionHandler = completion
+			webView.ready { preloadedWebView in
-		} else {
+				preloadedWebView.removeFromSuperview()
-			completeRequest(completion: completion)
+				self.replenishQueueIfNeeded()
+				completion(preloadedWebView)
+			}
+			return
+		}
+
+		assertionFailure("Creating PreloadedWebView in \(#function); queue has run dry.")
+		
+		let webView = PreloadedWebView(articleIconSchemeHandler: articleIconSchemeHandler)
+		webView.ready { preloadedWebView in
+			self.replenishQueueIfNeeded()
+			completion(preloadedWebView)
 		}
 	}
 	
-	func enqueueWebView(_ webView: WKWebView) {
+	func enqueueWebView(_ webView: PreloadedWebView) {
 		guard queue.subviews.count < maximumQueueDepth else {
 			return
 		}
-
-		webView.configuration.userContentController.add(WrapperScriptMessageHandler(self), name: MessageName.domContentLoaded)
 		queue.insertSubview(webView, at: 0)
-
+		webView.preload()
-		webView.loadFileURL(ArticleRenderer.page.url, allowingReadAccessTo: ArticleRenderer.page.baseURL)
-	}
-
-	// MARK: WKNavigationDelegate
-	
-	func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
-		if waitingForFirstLoad {
-			waitingForFirstLoad = false
-			if let completion = waitingCompletionHandler {
-				DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
-					self.completeRequest(completion: completion)
-					self.waitingCompletionHandler = nil
-				}
-			}
-		}
 	}
 	
 }
-
-// MARK: WKScriptMessageHandler
-
-extension WebViewProvider: WKScriptMessageHandler {
-
-	func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
-		switch message.name {
-		case MessageName.domContentLoaded:
-			if waitingForFirstLoad {
-				waitingForFirstLoad = false
-				if let completion = waitingCompletionHandler {
-					DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
-						self.completeRequest(completion: completion)
-						self.waitingCompletionHandler = nil
-					}
-				}
-			}
-		default:
-			return
-		}
-	}
-	
-}
-
-// MARK: Private
-
-private extension WebViewProvider {
-	
-	func completeRequest(completion: @escaping (WKWebView) -> ()) {
-		if let webView = queue.subviews.last as? WKWebView {
-			webView.removeFromSuperview()
-			webView.configuration.userContentController.removeScriptMessageHandler(forName: MessageName.domContentLoaded)
-			replenishQueueIfNeeded()
-			completion(webView)
-			return
-		}
-
-		assertionFailure("Creating WKWebView in \(#function); queue has run dry.")
-		let webView = WKWebView(frame: .zero)
-		completion(webView)
-	}
-
-	func buildConfiguration() -> WKWebViewConfiguration {
-		let preferences = WKPreferences()
-		preferences.javaScriptCanOpenWindowsAutomatically = false
-		preferences.javaScriptEnabled = true
-
-		let configuration = WKWebViewConfiguration()
-		configuration.preferences = preferences
-		configuration.setValue(true, forKey: "allowUniversalAccessFromFileURLs")
-		configuration.allowsInlineMediaPlayback = true
-		configuration.mediaTypesRequiringUserActionForPlayback = .video
-		configuration.setURLSchemeHandler(articleIconSchemeHandler, forURLScheme: ArticleRenderer.imageIconScheme)
-		
-		return configuration
-	}
-}