Sync with iCloud
iCloud sync is turned on by default when you download the app, so that your data is backed up and safe. You must make sure you have iCloud drive enabled for this to take place. iCloud sync allows you to sync between several of your own devices on the same iCloud account. It also allows you to get your data back onto a new device if you upgrade or change phones.
Sharing can only occur with the same iCloud account. So if there’s a family iPad lying around, then the contents will be on that. However if each family member has their own iCloud account, then each app will have its own set of contents.
The same label can be scanned by multiple people though, so if you have a label on a box with holiday decorations, then everyone can take a snap shot of the contents and add it to their app along with other items.
Sync with Dropbox
Sync via Dropbox allows you to share one set of data with other devices and/or people. When you choose to sync with Dropbox, it will suspend your iCloud sync but all the current data will be left in iCloud.
If your Dropbox has never been used to sync the Quick Peek app, then turning Dropbox sync on will make a new folder in your Dropbox called Quick Peek. You can then go to your Dropbox sharing preferences and share this folder with other people.
When someone wants to join your shared Dropbox folder, they simply enable the Dropbox sync in their Quick Peek app and login to their Dropbox account, after having received the shared file in their Dropbox. The app will recognize that a file exists and will give you a warning that all your local data will be replaced with the data from DropBox.
When sharing the Dropbox folder, you can choose to make it "view only" for one or all members who join. Note though, the app will allow them to add, move, and delete items on their device but all their changes will be overwritten and revert back to the state the app was in previously.
Disclaimer: Self-printed E labels require each person has enough credits to view shared boxes.
Switching between iCloud and Dropbox
It is possible to switch back to iCloud from Dropbox and vice versa so long as each time you switch, you make sure to choose to replace the data on your phone with the data from the cloud. This actually allows you to have separate datasets that can be used interchangeably.