How to AirDrop from iPhone to Mac and Mac to iPhone
AirDrop lets users wirelessly send files between Apple devices. Because it uses Bluetooth technology, it relies on devices being in close physical proximity to each other. It's a handy way to quickly share files, photos, etc. without the need to draft an email or message. Plus, AirDrop files are encrypted, so it's also secure.
Make sure you follow these steps beforehand so that you're good to go:
Turn on Bluetooth and WiFi. You do not need to be connectedto a WiFi network but the WiFi setting does need to be on. Also, turn off your hotspot if it's on. AirDrop won't work otherwise.
Make sure that the devices are within range of each other — no more than about 30 feet apart.
Check the AirDrop sharing settings of the device that is receiving the file. The settings are "Receiving Off," "Contacts Only," or "Everyone." If you choose to only receive files from contacts, make sure that the owner of the device sending the file is saved as a contact. You can adjust these settings in your Control Center or by going to "Settings" > "General" > "AirDrop."
How to AirDrop from iPhone to Mac
Open the file that you want to AirDrop, then tap the share icon, which is the square with the upwards-facing arrow.
Open sharing settings by tapping on this icon Credit: Apple That will show you all of the ways you can share a file. Tap the AirDrop icon, which is the concentric circles with a triangle cut out at the bottom.
AirDrop is the icon with the blue concentric circles Credit: apple From there, select the user/device that you'd like to send it to. Tapping the user/device automatically starts the AirDrop process. If no devices are showing up, double-check that all of your settings are correct.
Tap the device where you want to send the file. Credit: apple To accept an AirDrop on your Mac, a preview window will pop up on your device asking you to accept or decline the transfer. If you accept the AirDrop, it will show up in the same app it was sent from (a photo sent via AirDrop will show up in your photos app.)
On your Mac, click accept to receive the file. Credit: apple 
Choose where you want to save your file Credit: apple How to AirDrop from Mac to iPhone
There are a few different ways you can share a file via AirDrop on a Mac.
1. From Finder
Locate the file you want to share. Instead of opening it, control-click/right-click on the file. In the dropdown, go to "Share" then choose AirDrop from the menu.
Go to "Share" in the dropdown. Credit: apple 
Then hit AirDrop. Credit: Apple When the AirDrop window pops up, select the device to which you want to share.
Select the iPhone device to start the AirDrop. Credit: apple 2. From the open file
If the file that you want to share is already open, you can AirDrop from the toolbar of the open application. Find "Share" then AirDrop from the pop-out menu. The "Share" button will usually be under "File," but might be its own section in the Toolbar or in another section, depending on the app.
Go to "File" > "Share" > "AirDrop." Credit: Apple 3. Drag and drop
Last but not least, in the "Finder" window, you can drag and drop the file into AirDrop. Click and hold down on the file and drag it into the AirDrop section located under "Favorites." Still holding down on the file, drag and drop it over the receiving device.
Hover your file over the device until it's highlighted, then drop the file into the device. Credit: apple