Here are the steps to taking a screenshot on Snap Chat on for iPhone on iOS.
To take a screenshot on Shapchat, press on the menu and select “Take a screenshot.” With Snapchat, you can control how long your friends can view your message or pictures. You can also set how long to view your pictures and then it disappears forever.
You gotta time it right though, as Snapchat is designed so you can only see the message for a limited amount of time and you cannot take a screen capture of it.
1. Wait till the timer on the photo you receive hits 2.
2. Once it hits two, hold the lock button and wait till the timer hits 1.
3. When the timer hits 1 press and hold the home button.
Once this is done correctly you should have a screenshot of your Snapchat.