[beders]

Just in case you don't get it:

The moment the information is unencrypted and made available via a userinterface, you've lost all control.

You don't control the iOS rendering loop. You don't control the Android rendering system. (You might think you do though as much of Android is open source).

You don't control the OS core libraries, you don't control the microcode of the CPU. You don't control the blitting to a screen device or the recording of photons on a camera. And I'm not even talking about external manipulation to exfiltrate data.

You might control the content of the IP packages sent. You don't control any other IP packages sent.

[lostmsu]

You forgot that somebody can snoop on the unencrypted image on your screen.