To get that beautiful, silky effect of long exposure images, you would normally have to have a tripod, and a very steady hand. On the iPhone 7 (and higher), if you have updated to IOS 11 or above, you can achieve this without the need for extra equipment.
First of all, make sure your camera setting is on ‘Live’ mode (top, middle icon next to HDR). When this is on, it will turn yellow and briefly say ‘LIVE’.
Compose your photo, with a bit extra on the side as it slightly reduces the size when finished.
Press the shutter once, keep still, and wait a couple of seconds until the LIVE word has been and gone.
Go to your photos, and select the image. Swipe upwards (on the image) and you will see some effects . Scroll to the right, and you will see ‘Long Exposure’. Select this, and you will see your photo change into a beautiful, silky photo. This doesn’t work on all photos – only those with movement, especially on moving water. Don’t forget to turn the LIVE effect off once you have taken your shot!!!