Basic Sinch Sample in Swift - but no Sound - swift

Question

first of all thank you for reading my lines.
For an idea I'm currently trying to dive into the Swift world (I only have very basic programming knowledge - no Objective C knowledge
).
I tried to set up the following lines to create a very basic app-to-app sample in Sinch. After my code I let you know what the issues are.
import UIKit
import Sinch
var appKey = "APP_KEY_FROM_MY_ACCOUNT"
var hostname = "clientapi.sinch.com"
var secret = "SECRET_FROM_MY_ACCOUNT"
class CViewController: UIViewController, SINCallClientDelegate, SINCallDelegate, SINClientDelegate {
var client: SINClient?
var call: SINCall?
var audio: SINAudioController?
//Text field in the main storyboard
#IBOutlet weak var userNameSepp: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
self.initSinchClient()
}
//initialize and start the client as a fixed "userA"
func initSinchClient() {
client = Sinch.client(withApplicationKey: appKey, applicationSecret: secret, environmentHost: hostname, userId: "userB")
client?.call().delegate = self
client?.delegate = self
client?.startListeningOnActiveConnection()
client?.setSupportCalling(true)
client?.start()
}
//Did the Client start?
func clientDidStart(_ client: SINClient!) {
print("Hello")
}
//Did the Client fail?
func clientDidFail(_ client: SINClient!, error: Error!) {
print("Good Bye")
}
//Call Button in the main.storyboard ... if call==nil do the call ... else hangup and set call to nil
//the background color changes are my "debugging" :D
#IBAction func callSepp(_ sender: Any) {
if call == nil{
call = client?.call()?.callUser(withId: userNameSepp.text)
//for testing I change to callPhoneNumber("[phone]").
// the phone call progresses (but I hear nothing),
// the phonecall gets established (but I hear nothing)
// and the phonecall gets ended (but of course I hear nothing)
self.view.backgroundColor = UIColor.red
call?.delegate = self
audio = client?.audioController()
}
else{
call?.hangup()
self.view.backgroundColor = UIColor.blue
call = nil
}
}
func callDidProgress(_ call: SINCall?) {
self.view.backgroundColor = UIColor.green
client?.audioController().startPlayingSoundFile("/LONG_PATH/ringback.wav", loop: true)
print("Call in Progress")
}
//I know that this works but I don't hear anything
func callDidEstablish(_ call: SINCall!) {
client?.audioController().stopPlayingSoundFile()
print("Call did Establish")
}
func callDidEnd(_ call: SINCall!) {
print("Call did end")
}
// this works fine
#IBAction func hangUpSepp(_ sender: Any) {
call?.hangup()
self.view.backgroundColor = UIColor.red
call = nil
}
// i work in a "sub view controller" - so i navigate here back to the main view controller
#IBAction func goBackMain(_ sender: Any) {
call?.hangup()
dismiss(animated: true, completion: nil)
client?.stopListeningOnActiveConnection()
client?.terminateGracefully()
client = nil
}
}
So I can call my private phone number or if I change to callUser I can call another app but I don't hear anything. What do I miss? It must have to do with the SINAudioController and the client's method audioController() but I don't know what I'm doing wrong. Thank you for your help.