React Native Prevent Screenshot

Prevent Capture Screen

Android

• Prevent capture screen by setFlag secure

getWindow().setFlags(WindowManager.LayoutParams.FLAG_SECURE, WindowManager.LayoutParams.FLAG_SECURE);

• If you want to remove flag secure

getWindow().clearFlags(WindowManager.LayoutParams.FLAG_SECURE);

iOS

You can't prevent screen capture on iOS.

I have suggested 2 methods

1. After the user capture screen (UIApplicationUserDidTakeScreenshot), send the capture event to the server or display a warning message.
2. Try ScreenShieldKit (https://screenshieldkit.com). You can read more from this article. https://medium.com/nomtek/screenshot-preventing-on-mobile-apps-9e62f51643e9

Hide Preview Screenshot

Android

• SetFlag secure already hide preview screenshot

getWindow().setFlags(WindowManager.LayoutParams.FLAG_SECURE, WindowManager.LayoutParams.FLAG_SECURE);

iOS

• Overlay screen by added 2 two into appDelegate.m

- (void)applicationWillResignActive:(UIApplication *)application {

// fill screen with our own colour
UIView *colourView = [[UIView alloc]initWithFrame:self.window.frame];
colourView.backgroundColor = [UIColor whiteColor];
colourView.tag = 1234;
colourView.alpha = 0;
[self.window addSubview:colourView];
[self.window bringSubviewToFront:colourView];

// fade in the view
[UIView animateWithDuration:0.5 animations:^{
  colourView.alpha = 1;
}];
}

- (void)applicationDidBecomeActive:(UIApplication \*)application {
// grab a reference to our coloured view
UIView \*colourView = [self.window viewWithTag:1234];
// fade away colour view from main view
[UIView animateWithDuration:0.5 animations:^{
colourView.alpha = 0;
} completion:^(BOOL finished) {
// remove when finished fading
[colourView removeFromSuperview];
}];
}

References

• http://pinkstone.co.uk/how-to-control-the-preview-screenshot-in-the-ios-multitasking-switcher/
• https://stackoverflow.com/a/48228319/1754750
• https://medium.com/nomtek/screenshot-preventing-on-mobile-apps-9e62f51643e9