How to block Screenshots in your flutter app

when building highly secured apps, it can be essential to stop the user from taking screenshots, while this is quite straightforward on Android, it gets a little bit tricky on the iOS part. I remember facing this challenge some months ago and I scanned through a couple of StackOverflow answers for hours, I was at the point of getting frustrated when I stumbled on one that was the solution for the iOS part:

For Android:

1. inside your mainActivity.(java/tk), import the following:

import io.flutter.embedding.android.FlutterFragmentActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant
import android.view.WindowManager.LayoutParams

1. and you replace the content with:

class MainActivity: FlutterFragmentActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        window.addFlags(LayoutParams.FLAG_SECURE)
        GeneratedPluginRegistrant.registerWith(flutterEngine)
    }
}

this does it for Android.

For iOS:

1. in your AppDelegate.swift you should create a window extension just like below:

  extension UIWindow {
  func makeSecure() {
      let field = UITextField()
        let view = UIView(frame: CGRect(x: 0, y: 0, width: field.frame.self.width, height: field.frame.self.height))
        field.isSecureTextEntry = true
        self.addSubview(field)
        self.layer.superlayer?.addSublayer(field.layer)
        field.layer.sublayers?.last!.addSublayer(self.layer)
        field.leftView = view
        field.leftViewMode = .always
    }
  }

then call the new window extension in your application function:

self.window.makeSecure()

your AppDelegate.swift should look like this:

import UIKit
import Flutterimport UIKit
import Flutter

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    self.window.makeSecure()
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

  extension UIWindow {
  func makeSecure() {
      let field = UITextField()
      field.isSecureTextEntry = true
      self.addSubview(field)
      field.centerYAnchor.constraint(equalTo: self.centerYAnchor).isActive = true
      field.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
      self.layer.superlayer?.addSublayer(field.layer)
      field.layer.sublayers?.first?.addSublayer(self.layer)
    }
  }

thank you for reading, I hope this was helpful.