By Rachel Metz:

 

"A new app called Yovo aims to make disappearing messages truly short-lived by foiling a recipient’s attempts to take screenshots.

Like Snapchat and other ephemeral-messaging apps, Yovo lets you send photos with notes on them that can be viewed for a limited amount of time before they self-destruct. But Yovo, available Wednesday and initially only for the iPhone, also includes a feature called D-fence that yields only an image interrupted by opaque vertical bars when you try to take a screenshot or a photo with another camera."

 

   http://www.technologyreview.com/news/531521/an-optical-trick-makes-disappearing-messages-harder-to-screenshot/