How to Send a Screenshot to iPhone With Universal Clipboard

Use Universal Clipboard to copy a screenshot on your Mac and paste it on your iPhone, plus the Handoff, Wi-Fi, and Bluetooth settings it requires.

1. Sign both devices into one account. Universal Clipboard works only between devices signed in to the same Apple Account. Check on the Mac at the top of the System Settings sidebar, and on the iPhone at the top of the Settings list. Two accounts, no shared clipboard.
2. Turn on Wi-Fi, Bluetooth, and Handoff. Both devices need Wi-Fi and Bluetooth switched on and need to be near each other. On the Mac, open System Settings > General > AirDrop & Handoff and switch on Allow Handoff between this Mac and your iCloud devices.
3. Enable Handoff on the iPhone. On the iPhone, open Settings > General and find the AirPlay and Continuity section, then switch on Handoff. On older iOS versions the same switch sits under AirPlay & Handoff. Nothing pairs and nothing confirms. The switch is the entire setup.
4. Copy the screenshot instead of saving it. Add Control to any screenshot shortcut and the image goes to the clipboard rather than to a file. Command + Control + Shift + 4 for a selection, Command + Control + Shift + 3 for the whole screen. No file is written anywhere.
5. Paste on the iPhone. Open Messages, Notes, Mail, or any app that accepts an image. Touch and hold in the text field and choose Paste. The screenshot arrives at full resolution. A large image can take a moment while the transfer finishes in the background.