How Bluesky draws its logo on screenshots
When taking screenshots of posts on Bluesky, the logo in the corner disappears and is replaced by the "Follow" button. This is because the Bluesky app uses a trick that involves iOS's privacy-sensitive API. The logo is hidden during a screenshot, allowing it to appear in the image. This is achieved by creating a UITextField with the isSecureTextEntry property set to true and rendering the button into that field's .layer.
When a screenshot is taken, iOS hides this UITextField by blanking the layer, revealing the logo. For other platforms, the content is rendered as-is without masking. The behavior is not consistent when switching between apps, as iOS takes a snapshot at the start of the gesture, without triggering blanking. While some people in the thread found the trick nifty, others disliked it.
Telegram and Signal have also implemented similar behavior for their secret chats, and the technique is well-known enough that it is unlikely to be patched by Apple anytime soon.
Written by urgent.news from Lobsters's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
