Merge pull request #79 from pwa-builder/bugfix-4831-change-cache-strategy-in-network-error

Attempting to change the cache strategy when there is a network error #4831

Author: JudahGabriel

Microsoft.PWABuilder.IOS.Web/Resources/ios-project-src/pwa-shell/ViewController.swift

@@ -4,7 +4,11 @@ import WebKit
 var webView: WKWebView! = nil
 
 class ViewController: UIViewController, WKNavigationDelegate, UIDocumentInteractionControllerDelegate {
-    
+    enum LoadingMode {
+        case defaultCachePolicy
+        case forceCache
+    }
+
     var documentController: UIDocumentInteractionController?
     func documentInteractionControllerViewControllerForPreview(_ controller: UIDocumentInteractionController) -> UIViewController {
         return self
@@ -17,6 +21,7 @@ class ViewController: UIViewController, WKNavigationDelegate, UIDocumentInteract
     var toolbarView: UIToolbar!
 
     var htmlIsLoaded = false;
+    private var loadingMode = LoadingMode.defaultCachePolicy
 
     private var themeObservation: NSKeyValueObservation?
     var currentWebViewTheme: UIUserInterfaceStyle = .unspecified
@@ -124,8 +129,22 @@ class ViewController: UIViewController, WKNavigationDelegate, UIDocumentInteract
         webviewView.addSubview(toolbarView)
     }
 
-    @objc func loadRootUrl() {
-        PWAShell.webView.load(URLRequest(url: SceneDelegate.universalLinkToLaunch ?? SceneDelegate.shortcutLinkToLaunch ?? rootUrl))
+    @objc func loadRootUrl(cachePolicy: NSURLRequest.CachePolicy = .useProtocolCachePolicy) {
+        CloudpilotEmu.webView.load(URLRequest(url: SceneDelegate.universalLinkToLaunch ?? SceneDelegate.shortcutLinkToLaunch ?? rootUrl, cachePolicy: cachePolicy))
+    }
+    
+    func reloadWebview(
+        loadingMode: LoadingMode = LoadingMode.defaultCachePolicy
+    ) {
+        switch loadingMode {
+        case LoadingMode.defaultCachePolicy:
+            loadRootUrl(cachePolicy: .useProtocolCachePolicy);
+
+        case LoadingMode.forceCache:
+            loadRootUrl(cachePolicy: .useProtocolCachePolicy);
+        }
+
+        self.loadingMode = loadingMode
     }
 
     func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!){
@@ -147,19 +166,24 @@ class ViewController: UIViewController, WKNavigationDelegate, UIDocumentInteract
     func webView(_ webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: Error) {
         htmlIsLoaded = false;
 
-        if (error as NSError)._code != (-999) {
-            self.overrideUIStyle(toDefault: true);
+        if (error as NSError)._code == (-999) { return }
+        
+        self.overrideUIStyle(toDefault: true);
+        webView.isHidden = true;
+        loadingView.isHidden = false;
 
-            webView.isHidden = true;
-            loadingView.isHidden = false;
+        if loadingMode == LoadingMode.defaultCachePolicy {
+            DispatchQueue.main.async {
+                self.reloadWebview(loadingMode: LoadingMode.forceCache)
+            }
+        } else {
             animateConnectionProblem(true);
-            
             setProgress(0.05, true);
-
+            
             DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
                 self.setProgress(0.1, true);
                 DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
-                    self.loadRootUrl();
+                    self.reloadWebview()
                 }
             }
         }