iOS Question Prevent screenshot iOS

Private Sub Application_Start (Nav As NavigationController)
   NavControl = Nav
   Page1.Initialize("Page1")
   Page1.Title = "Page 1"
   Page1.RootPanel.Color = Colors.White
   NavControl.ShowPage(Page1)
   Dim no As NativeObject = Me
   no.RunMethod("addListener", Null)
End Sub

#if OBJC
- (void)addListener {
  [[NSNotificationCenter defaultCenter] addObserver:self
  selector:@selector(_screenshot_taken)
  name:UIApplicationUserDidTakeScreenshotNotification  object:nil];
}
#end if

Private Sub Screenshot_Taken
   Log("Screenshot taken")
End Sub

You cannot directly block UIApplicationUserDidTakeScreenshotNotification from firing to prevent a screenshot; it only notifies you after it happens. To actually prevent screen capture, you must apply isSecureTextEntry to a hidden UITextField, which tricks iOS into masking the screen with black.

Implementation in Objective-C
To secure a specific view, use a UITextField set to secureTextEntry.

Click to expand...

#if OBJC
- (void)preventScreenCapture {
// 1. Create a UITextField
UITextField *field = [[UITextField alloc] init];
field.secureTextEntry = YES;

// 2. Add to your current view
[self.view addSubview:field];

// 3. Make the secure layer cover your desired content
// Typically requires setting up constraints to fill the screen/view
field.layer.sublayers.firstObject.delegate = self;

// 4. Hide the text field itself
field.hidden = YES;
}
#endif

Click to expand...