feat: Allow plugins to override navigation (#2872)

Co-authored-by: Sean Bannigan <bannigan@meetmaestro.com>

Author: jcesarmobile

android/capacitor/src/main/java/com/getcapacitor/Bridge.java

@@ -224,6 +224,19 @@ private void loadWebView() {
   }
 
   public boolean launchIntent(Uri url) {
+    /*
+    * Give plugins the chance to handle the url
+    */
+    for (Map.Entry<String, PluginHandle> entry : plugins.entrySet()) {
+      Plugin plugin = entry.getValue().getInstance();
+      if (plugin != null) {
+        Boolean shouldOverrideLoad = plugin.shouldOverrideLoad(url);
+        if (shouldOverrideLoad != null) {
+          return shouldOverrideLoad;
+        }
+      }
+    }
+
     if (!url.toString().contains(appUrl) && !appAllowNavigationMask.matches(url.getHost())) {
       try {
         Intent openIntent = new Intent(Intent.ACTION_VIEW, url);

android/capacitor/src/main/java/com/getcapacitor/Plugin.java

@@ -5,6 +5,7 @@
 import android.content.Intent;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
+import android.net.Uri;
 import android.os.Bundle;
 
 import androidx.appcompat.app.AppCompatActivity;
@@ -548,6 +549,15 @@ protected void handleOnStop() {}
    */
   protected void handleOnDestroy() {}
 
+  /**
+   * Give the plugins a chance to take control when a URL is about to be loaded in the WebView.
+   * Returning true causes the WebView to abort loading the URL.
+   * Returning false causes the WebView to continue loading the URL.
+   * Returning null will defer to the default Capacitor policy
+   */
+  @SuppressWarnings("unused")
+  public Boolean shouldOverrideLoad(Uri url) { return null; }
+
   /**
    * Start a new Activity.
    *

ios/Capacitor/Capacitor/CAPBridgeViewController.swift

@@ -252,6 +252,29 @@ public class CAPBridgeViewController: UIViewController, CAPBridgeDelegate, WKScr
   public func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
     NotificationCenter.default.post(name: Notification.Name(CAPNotifications.DecidePolicyForNavigationAction.name()), object: navigationAction)
     let navUrl = navigationAction.request.url!
+    
+    /*
+     * Give plugins the chance to handle the url
+     */
+    if let plugins = bridge?.plugins {
+      for pluginObject in plugins {
+        let plugin = pluginObject.value
+        let selector = NSSelectorFromString("shouldOverrideLoad:")
+        if plugin.responds(to: selector) {
+          let shouldOverrideLoad = plugin.shouldOverrideLoad(navigationAction)
+          if (shouldOverrideLoad != nil) {
+            if (shouldOverrideLoad == true) {
+              decisionHandler(.cancel)
+              return
+            } else if shouldOverrideLoad == false {
+              decisionHandler(.allow)
+              return
+            }
+          }
+        }
+      }
+    }
+    
     if let allowNavigation = allowNavigationConfig, let requestHost = navUrl.host {
       for pattern in allowNavigation {
         if matchHost(host: requestHost, pattern: pattern.lowercased()) {
@@ -267,8 +290,6 @@ public class CAPBridgeViewController: UIViewController, CAPBridgeDelegate, WKScr
       return
     }
 
-    // TODO: Allow plugins to handle this. See
-    // https://github.com/ionic-team/cordova-plugin-ionic-webview/blob/608d64191405b233c01a939f5755f8b1fdd97f8c/src/ios/CDVWKWebViewEngine.m#L609
     decisionHandler(.allow)
   }
 

ios/Capacitor/Capacitor/CAPPlugin.h

@@ -24,6 +24,13 @@
 - (void)addListener:(CAPPluginCall *)call;
 - (void)removeListener:(CAPPluginCall *)call;
 - (void)removeAllListeners:(CAPPluginCall *)call;
+/**
+ * Give the plugins a chance to take control when a URL is about to be loaded in the WebView.
+ * Returning true causes the WebView to abort loading the URL.
+ * Returning false causes the WebView to continue loading the URL.
+ * Returning nil will defer to the default Capacitor policy
+ */
+- (NSNumber *)shouldOverrideLoad:(WKNavigationAction *)navigationAction;
 
 // Called after init if the plugin wants to do
 // some loading so the plugin author doesn't