macOS clearing the general pasteboard?

[binkley]

I've been searching for a way to ensure that my objective-c/cocoa application can clear the general pasteboard when it exits. So far every tutorial/doc that I've found will tell you how to add data to the pasteboard, but not delete it.

For example, I have the following code in my app:

NSPasteboard *pb = [NSPasteboard generalPasteboard];
[pb declareTypes: [NSArray arrayWithObject:NSStringPboardType] owner: self];
[pb setString: @"foo" forType: NSStringPboardType];

I've tried using the same code in my AppController's dealloc routine using the string @"", but I can still paste "foo" well after the application exits. Any ideas?

 

[Eraserhead]

Why do you want to do this?

 

[binkley]

Why do you want to do this?

The user will be expected to copy some security sensitive information to the pasteboard. In addition to wanting this information to be removed upon exit, I'll also be setting up a timer to delete it after a set period of time.

 

[lancestraz]

This works for me:

NSPasteboard *pb = [NSPasteboard generalPasteboard];
[pb declareTypes: [NSArray arrayWithObject:NSStringPboardType] owner: pb];
[pb setString: @"" forType: NSStringPboardType];

 

[Eraserhead]

Its a security risk copying it to the pasteboard at all as someone could very easily make an application run in the background and get the sensitive information.

I would try another technique (a button in the interface and writing your own code to "copy" the information) if possible.

To solve your problem you could just copy a random string (or number) to the pasteboard to "clear" it, but you need to check the user hasn't copied anything else since otherwise that would be really really irritating.

 

[binkley]

Aside from the wisdom of using this technique.. maybe my dealloc routine is never being called? Where would the best place be to put code to make sure the pasteboard is cleared when the program exits?

 

[Eraserhead]

Aside from the wisdom of using this technique..

I regularly cut items to the pasteboard for later use. If I was using an application which then went and overwrote that I wouldn't be happy, and I simply wouldn't use the application (i'd probably give it a 1* review too).

If you can store the data programatically that would be a far better solution.

But with that caveat:

Where would the best place be to put code to make sure the pasteboard is cleared when the program exits?

delegate NSApp to one of your files and then use,

-(NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender;

 

[binkley]

I appreciate your help. Believe me, the users of this application would expect this behavior. They'd be far more concerned if the pasteboard was left intact rather than deleted unexpectedly.

 

[binkley]

I set up my AppController as a delegate and implemented the following routine and everything works fine:

- (NSApplicationTerminateReply) applicationShouldTerminate: (NSApplication *) sender 
{

  NSPasteboard *pb = [NSPasteboard generalPasteboard];
  [pb declareTypes: [NSArray arrayWithObject:NSStringPboardType] owner: self];
  [pb setString: @"" forType: NSStringPboardType];

  return NSTerminateNow;
}

Thanks again.