iOS 10 doesn't print NSLogs

It could be that you added the property "OS_ACTIVITY_MODE": "disable" in the Scheme environment variables (to hide OS output from the simulator) and forgot about it, and now are running on a real device.

In Xcode 8:

Product -> Scheme -> Edit Scheme -> Run -> Arguments -> Environment Variables

Only add OS_ACTIVITY_MODE and check it（Don't add a value）

Summary: This is a bug of Xcode 8 + iOS10, we can solve it in this way:

• When using the simulator, add the Name "OS_ACTIVITY_MODE" and the Value "disable" and check it.

• When on a real device, only add "OS_ACTIVITY_MODE" and check it（Don't add the Value）. You will see the NSLog in the Xcode8 Console.

If you check the Xcode 8 beta release notes, you'll find that it says:

When debugging an app running on Simulator, logs may not be visible in the console. Workaround: Use command + / in Simulator.app to open the system log in the Console app to view NSLogs. (26457535)