ios - change a property in another viewcontroller

Question

I've searched how to run a method from another ViewController on stackoverflow and didn't find an answer. I have a ViewController1 playing an audio using AVAudioPlayer and I want my ViewController2 to be able to change it's volume.

I've tried the basic: calling a method in ViewController2 that changes the volume in ViewController1.
This doesn't work. The method is able do output Logs but isn't able to change properties.

Thanks

Answer 1

You need to pass a message from ViewController2 to ViewController1.
For that either use:
1. Notifications
2. Delegation

Here is the link for a tutorial if you are unaware of both of them.
http://devinsheaven.com/cocoa-tutorial-passing-messages-between-objects-notifications-delegates-and-target-action/