With apps like Facebook Poke or SnapChat the content you're sending is ephemeral (it won't be around forever).
Developers of these types of apps can't necessarily prevent a screenshot from happening but you they can at least notify the user who sent the content that a screenshot was taken, which in turn lets them know not to trust the receiver.
Developers of these types of apps can't necessarily prevent a screenshot from happening but you they can at least notify the user who sent the content that a screenshot was taken, which in turn lets them know not to trust the receiver.