If your iPhone's camera roll is getting a bit out of hand and taking up a lot of space, you'll need to mass delete some photos. The Sweet Setup reminds us that the quickest way to do that on a Mac is with Image Capture.
Just connect your phone to your Mac, launch Image Capture, then press Command+A to select all the images. Hit the red delete icon, and all the photos on your phone will be deleted in an instant. Just make sure you have backups before you do this (or click the "Import All" button to import them onto your Mac).