Redirect rules: for example, twitter->nitter

App/Backend/PersonalRedirectRules.swift

@@ -0,0 +1,24 @@
+//
+//  PersonalRedirectRules.swift
+//  App
+//
+//  Created by James Magahern on 9/30/20.
+//
+
+import Foundation
+
+class PersonalRedirectRules
+{
+    func redirectedURL(for url: URL) -> URL? {
+        if var components = URLComponents(url: url, resolvingAgainstBaseURL: false) {
+            
+            // Rule for nitter.net
+            if url.host == "twitter.com" {
+                components.host = "nitter.net"
+                return components.url
+            }
+        }
+        
+        return nil
+    }
+}

App/Browser View/BrowserViewController.swift

@@ -21,6 +21,7 @@ class BrowserViewController: UIViewController, WKNavigationDelegate, WKUIDelegat
     private let toolbarController = ToolbarViewController()
     
     private let autocompleteViewController = AutocompleteViewController()
+    private let redirectRules = PersonalRedirectRules()
     
     private var policyManager: ResourcePolicyManager { tabController.policyManager }
     
@@ -373,7 +374,15 @@ class BrowserViewController: UIViewController, WKNavigationDelegate, WKUIDelegat
         }
         
         preferences.allowsContentJavaScript = allowJavaScript
-        decisionHandler(.allow, preferences)
+        
+        if let url = navigationAction.request.url,
+           let redirectedURL = redirectRules.redirectedURL(for: url)
+        {
+            tab.beginLoadingURL(redirectedURL)
+            decisionHandler(.cancel, preferences)
+        } else {
+            decisionHandler(.allow, preferences)
+        }
     }
     
     func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {