I was trying to free up some space the other day on my daughters iOS devices. They were out of space and couldn't take any more photos , etc.
The first thing I did was review all the apps that she doesn't use any more, after freeing up a good few Gb from this. I looked at the space usage and was shocked by the size the Messages application and WhatsApp was taking up.
As they had all the photos already imported into the albums then it was a copy of the photos to send to friends and family or ones they had received.
In WhatsApp it is nice and easy to clear these out. Go into a conversation, click on the name at the top of the screen. You will then see an option View All Media and it will be all the media files you have exchanged with that person, this may be photos or videos.
From here you can then click Select, choose all the media you want to remove, then you can click on the bin on the bottom right of the screen and they will be removed.
In iOS messages app again you click into the conversation, Then in the top right click on Details. Scroll down and you will see all the images you have sent or received. There is no easy way I can see to remove all of them at once, you need to click on the picture then delete it.
Once you have clicked on an image to view it, if you click again you will then get a list icon on the bottom right of the screen, from here you can easily see the list with the image name etc, so you could scroll through this way and remove the images.
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