Ensure your iPhone and Mac are signed in with the same Apple ID
Turn on Wi-Fi and Bluetooth on both devices
Keep both devices close to each other
On your Mac, open Control Center
Click Screen Mirroring
Select your iPhone if it appears
On your iPhone, open Control Center
Tap Screen Mirroring
Select your Mac if it appears
If prompted, enter the AirPlay code shown on the Mac
Use QuickTime Player on Mac if you want to mirror via cable
Connect your iPhone to your Mac with a USB cable
Open QuickTime Player
Click File
Click New Movie Recording
Click the arrow next to the record button
Select your iPhone as the camera source
Use a third-party app if AirPlay mirroring is not available
Update iPhone and Mac to the latest software if mirroring does not work