In April 2015, Apple reminded developers that as of June 2015 all apps and app updates submitted to the App Store must include 64-bit support. After more than a year, some apps are still stuck on 32 bits and lack support for 64-bit devices. iOS 10 takes a naming and shaming approach by including a brand new warning message that appears when you open a 32-bit app on a 64-bit iPhone, iPad or iPod touch.
iOS 10 tidbit: warning message when launching apps that aren’t 64-bit compliant