How to turn off apps sound when using headphones?

I remember in iOS 7, apps wouldn't sound on headphones when the phone was in silent mode and this was really cool 'cause I could listen to music while playing games. But now in iOS 8, apps still sound in headphones even when the phone is in silent mode, and it's kind of annoying having to turn off the sound of an individual app and later having to turn it on.

Is there any way to turn off apps sound on headphones? Or I still have to do the manual job?