Periscope now supports live streaming from your GoPro camera using your iPhone! Click here for Periscope's announcement.
Over 10 million Periscope users worldwide can now live stream from their GoPro HERO4 Silver, HERO4 Black, or HERO5 Black cameras and use all of the standard features found in the app. Users connect their GoPro camera to their iPhone using WiFi and Periscope allows them to live stream from the GoPro or switch between their front and rear facing iPhone cameras.
You can download Periscope from the Apple App or Google Play Store.
To get you started, check out this article on How to broadcast using a GoPro camera and Periscope.