I'm not sure how this app works, but Snapchat takes certain precautions to make screenshotting more difficult (the most obvious one being that you have to hold

I'm not sure how this app works, but Snapchat takes certain precautions to make screenshotting more difficult (the most obvious one being that you have to hold your finger on the screen or the image disappears, but I think there are also some technical safeguards as well). And as someone else pointed out, it tells the sender if the receiver screenshotted, which allows you to in formally determine whether or not you trust this person in the future.