I finally got the connection between TouchOSC and my app to work.
This is a key connection for my entire project: that the OSC signals can be received in the iphone apps that the performers will wear in their headsets.
This is made from the UnityOSC classes by Jorge Garcia Martin.
All assets from UnityOSC should be imported to the Unity file. The important thing is then to change the initialization of the IP addresses in the OSCHandler.init. This test is done over my own home wifi, but should be made on a local, ie. not connected to the internet, network. This should minimize the risk of fallouts, firewall blockings etc.
The IP address of the Host should be set to the iphone’s local IP address and should be changed from the sending part.