After receiving the call status monitoring demand, the screenshot status monitoring is added again. When using App, if the user needs to monitor the current status when performing screenshot operation, there are two methods below. One is to replace the screenshot image content (Plan A), the other is to pop up the prompt box (Plan B). The steps are as follows

  1 #pragma mark - Monitor screenshots
  2 // Plan A
  3 /**
  4  Screenshot of monitoring equipment
  5  */
  6 - (void)registerTakeScreenShotNotice {
  7     kWeakSelf(self);
  8     NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];
  9     [kNotificationCenter addObserverForName:UIApplicationUserDidTakeScreenshotNotification
 10                                      object:nil
 11                                       queue:mainQueue
 12                                  usingBlock:^(NSNotification * _Nonnull note) {
 13                                      
 14                                      NSLog(@"Test screenshots");
 15                                      [weakself userDidTakeScreenshot];//Screen response
 16                                  }];
 17 }
 18 /**
 19  Screenshots response
 20  */
 21 - (void)userDidTakeScreenshot {
 22     NSLog(@"Screenshot detected");
 23     //Artificial operation,Get screenshot data
 24     UIImage *image = [self imageWithScreenshot];
 25     NSLog(@"userDidTakeScreenshot:\n%@", image);
 26     
 27     UIImageView *imageScreenshot = [[UIImageView alloc] initWithImage:image];// here image Resources can be operated according to actual needs,Display the current screenshot or replace it with a fixed image, etc!
 28     imageScreenshot.frame = CGRectMake(SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2, SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2);
 29     [self.wkWebView addSubview:imageScreenshot];// Show in current View Hierarchy
 30 }
 31 /**
 32  Return to screenshot data
 33  
 34  @return Return to screenshot data
 35  */
 36 - (UIImage *)imageWithScreenshot {
 37     NSData *imageData = [self dataWithScreenshotInPNGFormat];
 38     return [UIImage imageWithData:imageData];
 39 }
 40 /**
 41  Get current screen
 42  
 43  @return Get current screen
 44  */
 45 - (NSData *)dataWithScreenshotInPNGFormat {
 46     // Source (Under MIT License):
 47     CGSize imageSize = CGSizeZero;
 48     UIInterfaceOrientation orientation = kApplication.statusBarOrientation;
 49     if (UIInterfaceOrientationIsPortrait(orientation)) {
 50         imageSize = SCREEN_RECT.size;
 51     }
 52     else {
 53         imageSize = CGSizeMake(SCREEN_HEIGHT, SCREEN_WIDTH);
 54     }
 55     
 56     UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
 57     CGContextRef context = UIGraphicsGetCurrentContext();
 58     for (UIWindow *window in [kApplication windows]) {
 59         CGContextSaveGState(context);
 60         CGContextTranslateCTM(context, window.center.x, window.center.y);
 61         CGContextConcatCTM(context, window.transform);
 62         CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
 63         
 64         // Correct for the screen orientation
 65         if (orientation == UIInterfaceOrientationLandscapeLeft) {
 66             CGContextRotateCTM(context, M_PI_2);
 67             CGContextTranslateCTM(context, 0, -imageSize.width);
 68         }
 69         else if (orientation == UIInterfaceOrientationLandscapeRight) {
 70             CGContextRotateCTM(context, -M_PI_2);
 71             CGContextTranslateCTM(context, -imageSize.height, 0);
 72         }
 73         else if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
 74             CGContextRotateCTM(context, M_PI);
 75             CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
 76         }
 77         
 78         if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]) {
 79             [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
 80         }
 81         else {
 82             [window.layer renderInContext:context];
 83         }
 84         
 85         CGContextRestoreGState(context);
 86     }
 87     
 88     UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
 89     UIGraphicsEndImageContext();
 90     
 91     return UIImagePNGRepresentation(image);
 92 }
 93  
 94 // Plan B
 95 - (void)intercepScreenshots {
 96 //    kWeakSelf(self);
 97 //    NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];
 98 //    [kNotificationCenter addObserverForName:UIApplicationUserDidTakeScreenshotNotification object:nil queue:mainQueue usingBlock:^(NSNotification * _Nonnull note) {
 99 //        [weakself checkScreenshots];
100 //    }];
101     [kNotificationCenter addObserver:self
102                             selector:@selector(checkScreenshots)
103                                 name:UIApplicationUserDidTakeScreenshotNotification
104                               object:nil];
105 }
106 - (void)checkScreenshots {
107     UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Tips"
108                                                         message:@"Do not screenshots"
109                                                        delegate:self
110                                               cancelButtonTitle:@"YES"
111                                               otherButtonTitles:@"NO", nil];
112     [alertView show];
113 }

This is the end of the sharing. I hope the content can help you in practice. If you have any shortcomings, please point out common progress!