Eventsquid has an app specifically designed for contact or lead scanning amongst your event attendees.
Your attendees can download the scanning app from the Apple App Store or the Google Play Store. They will be prompted to enter both your event ID (xxxxxx) and the authorization code you provide in the Configuration area.
You can include this code in confirmation email for all or only specific attendee types or use the Communcations Center to notify those who you wish to have access.
You may download the app and test it on QR codes you can access in the Event Details panel of any attendee.
Here is a video for you, the event host to get familiar with how it works.
Here is a video for you to share with your primary users of the app at your event (most commonly exhibitors, scanning for contact information from your attendees).