Hey there,
the Nextcloud app already provides a scan document feature. It would be great, to scan documents not only from camera as source but also from existing images from files (as Dropbox and other apps provide).
Thanks and cheers,
Momo
Have you tried to select “+” > “Scan from camera” and then touched the icon in the lower right corner?
I am running Nextcloud iOS 4.4.0 and there is no such icon in the lower right corner. This icon would solve this request! 
I’m personally not using iOS but please have a look on the screenshots provided on in the Apple App Store:
The “+” icon exists, the button in the lower right corner within the scan feature still does not exist (iOS 4.4.3).
Further improvements for the scan feature:
a) When scanning multiple pages (using the camera) there is a delay (up to 15 seconds!) after pressing the “save” button (seems to depend from the amount of scanned photos). There should be some kind of pop-up illustrating that the saving is in progress (and its progress), otherwise it may be hit again, which leads to a crash of the app and loss of taken photos for the scan. alternatively, the save button could be deactivated or something.
b) When saving the scan, the settings used for the last saving could be kept (e.g. quality)
c) After saving, there is a pop-up appearing asking whether images should be kept or deleted. This pop-up could be replaced with another checkbox within the saving settings. Thereby, the whole process is shortened and facilitated.