Testing Principle Prototypes

After you've created your test app in Principle, it's time to show the world!  (or at least some people to test it and provide feedback for you!)

(Your participants will need the Principle Mirror App to see your creation.)

You will be prompted to provide a URL for your prototype.    As Principle prototypes are not URL-based, you'll need to create a location.  The easiest way to do this is to put the .PRD files into Box, Google Drive, or Dropbox, using that URL.

The PRD file can then be downloaded by your participant from the public/shared Google Drive or Dropbox file that you've created and shared:


Next, the participant will tap "Open in Principle".


This will allow access via the installed Principle Mirror app, and you can get started with your study session!

(Note, this is easiest for a moderated session, so that you can help walk your participant through this process!)

From Principle's documentation:

If you'd like to share your design with others so that they can interact with it, they can install Principle Mirror on their iOS device (Please see note below about iOS 13) and you can send them the file. The file you share must have the .prd extension and cannot be zipped in order for iOS to open it in Principle Mirror.

  • Email--To open an attached PRD file from an email, tap the attachment and then the iOS share button. Select Principle Mirror in the sharing panel, or the "Open In..." button if Principle isn't visible.

  • Your own server--If you're concerned about using a file sharing service for security reasons, you can put the .prd file on your own FTP server. Share a direct link to the file and others can view it on their phone. Safari will show an "Open in Principle" button.

  • Dropbox, Google Drive, Box, etc--You can upload your .prd file to a file sharing service and generate a link to the file.

Note about Dropbox:
By default, Dropbox links will take you to a Dropbox page rather than to the file itself. You can bypass this by changing the end of the Dropbox link from "dl=0" to "dl=1"

Note about Google Drive:
The Google Drive app has problems with special file types, so we do not recommend using it to share Principle files.  

Note from Principle re: iOS 13:  Safari currently has a bug that will not allow the .prd file to be passed correctly to the download manager.  The file will simply not open.  Until it is fixed within Safari, you may have to opt for the Email option described above and use moderated testing for now.

The principle is best tested in a Native iOS set up, with the above stipulations.

It is *highly* recommended that you thoroughly test this while the study is in Preview Mode before launching to ensure it is working as you envision.

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