Which models does ios 10 invisible ink function support?

What is the invisible ink function of IOS 10? IOS 10 invisible ink function is actually a function that can make iMessage function more vivid and interesting. Where is the function of IOS 10 invisible ink? If you want to use it, you need to open 3D Touch in Settings-Accessibility. Can all Apple phones use the IOS 10 invisible ink function? Only iphone 6S and above mobile phones can be used. Ios 10 short message sending invisible ink method graphic tutorial: 1. This function is a new function of iMessage after upgrading ios 10. If you want to use it, you need to turn on 3D Touch in Settings-Accessibility (only available on 6s and above phones). 2. In iMessage, you can send a picture or text, and press and hold the send key, which is the blue arrow; 3. then the effect of sending it out is a layer of shiny things outside. Finally, you can see the original words with a stroke of your finger. 4. When you want to use the effect, after the text input is completed, press and hold the Send key to enter the effect selection interface.