IOS Auto Upload Photos

Open the Nextcloud app on your iPhone and select more on the lower right corner of the screen.

Then scroll to the end of the list and select Settings. 

Select Auto Upload at the top. 

Choose to enable auto-upload for photos and videos, and select the option to upload the entire camera roll. 

You may need to enable the "Auto Upload" toggle at the bottom of the screen. 

Ensure the Nextcloud app has permission to access your photos by going to your iPhone's main Settings > Nextcloud and setting Photos to "All Photos". 

Also, check Settings > Nextcloud and make sure Background App Refresh is enabled.