Hide the app contents while in the background

android/app/src/main/java/co/edgesecure/app/MainActivity.kt

@@ -1,7 +1,9 @@
 package co.edgesecure.app
 
 import android.content.pm.ActivityInfo
+import android.os.Build
 import android.os.Bundle
+import android.view.WindowManager
 import com.facebook.react.ReactActivity
 import com.facebook.react.ReactActivityDelegate
 import com.facebook.react.defaults.DefaultNewArchitectureEntryPoint.fabricEnabled
@@ -34,6 +36,17 @@ class MainActivity : ReactActivity() {
         // Do not pass the saved state, as required by react-native-screens:
         super.onCreate(null)
 
+        // Hide app contents in the background:
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            setRecentsScreenshotEnabled(false);
+        } else {
+            getWindow()
+                .setFlags(
+                    WindowManager.LayoutParams.FLAG_SECURE,
+                    WindowManager.LayoutParams.FLAG_SECURE
+                ) ;
+        }
+
         // Lock the app to portrait mode:
         if (resources.getBoolean(R.bool.portrait_only)) {
             requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT

ios/edge/AppDelegate.mm

@@ -16,7 +16,10 @@
 #import <sys/errno.h>
 #import <UserNotifications/UserNotifications.h>
 
-@implementation AppDelegate
+@implementation AppDelegate {
+  // Edge addition:
+  UIView *securityView;
+}
 
 // From https://reactnative.dev/docs/0.71/linking#enabling-deep-links
 - (BOOL)application:(UIApplication *)application
@@ -148,4 +151,34 @@ - (void)application:(UIApplication *)application
   }];
 }
 
+/**
+ * Hides the app when we go into the background.
+ * Edge addition.
+ */
+- (void)applicationDidEnterBackground:(UIApplication *)application
+{
+  UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"LaunchScreen" bundle:nil];
+  UIViewController *launchScreen = [storyboard instantiateInitialViewController];
+  if (launchScreen == nil) return;
+  UIView *launchView = launchScreen.view;
+  if (launchView == nil) return;
+
+  launchView.frame = self.window.bounds;
+  [self.window addSubview:launchView];
+  [self.window makeKeyAndVisible];
+  securityView = launchView;
+}
+
+/**
+ * Shows the app when we come into the foreground.
+ * Edge addition.
+ */
+- (void)applicationWillEnterForeground:(UIApplication *)application
+{
+  if (securityView != nil) {
+    [securityView removeFromSuperview];
+    securityView = nil;
+  }
+}
+
 @end