To share your Wi-Fi password between a Mac and an iPhone, make sure the Mac is running macOS 10.13 High Sierra or later. Also, update the iPhone to the latest version of iOS. You’ll also need to be signed in to an iCloud account with your Apple ID on each device. If you are using devices with two different iCloud accounts, ensure that each person has the other person’s address in their contacts on the device.

• Sign into the Mac and make sure it is connected to the Wi-Fi network whose password you’d like to share with the iPhone, then hold your iPhone near the Mac. On the iPhone, open the Settings app and tap “Wi-Fi.”

• In the list of available Wi-Fi networks, tap the name of the network you want to connect to (the one you’ll be receiving the password for.)
• If all went well, you’ll see a “Wi-Fi Password” pop-up appear in the upper-right corner of the screen on the Mac. It asks you if you want to share the password of your Wi-Fi hotspot with the iPhone. Click “Share.”

The Mac will wirelessly transmit the Wi-Fi network password to your iPhone, and your iPhone will connect to the network.