Disable Screen Capture/ScreenShot in React Native App

Android

Inside /android/app/src/main/java/com/{Project_Name}/MainActivity.java

you may add the following lines. Prevent capture screen by setFlag FLAG_SECURE, use code below as an example:

import android.os.Bundle;
import android.view.WindowManager;

...

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_SECURE, WindowManager.LayoutParams.FLAG_SECURE);
}

later when you want to remove secure flag

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

iOS

overlay screen in AppDelegate.m, take this example:

- (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];
    }];
}