NSError *setCategoryError = nil;
BOOL success = [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback
                                                      error: &setCategoryError];

NSError *activationError = nil;
[[AVAudioSession sharedInstance] setActive: YES error: &activationError];

…
NSLog(@"session.currentRoute.outputs count %d", [[[[AVAudioSession sharedInstance] currentRoute] outputs ] count]);
for (AVAudioSessionPortDescription *portDesc in [[[AVAudioSession sharedInstance] currentRoute] outputs ]) {
    NSLog(@"-----");
    NSLog(@"portDesc UID %@", portDesc.UID);
    NSLog(@"portDesc portName %@", portDesc.portName);
    NSLog(@"portDesc portType %@", portDesc.portType);
    NSLog(@"portDesc channels %@", portDesc.channels);
}

CFDictionaryRef asCFType = nil;
UInt32 dataSize = sizeof(asCFType);
AudioSessionGetProperty(kAudioSessionProperty_AudioRouteDescription, &dataSize, &asCFType);
NSDictionary *audioRoutesDesc = (__bridge NSDictionary *)asCFType;
NSLog(@"audioRoutesDesc %@", audioRoutesDesc);

self.myMPVolumeView.showsVolumeSlider = NO;

do
{
    try audioSession.setCategory(AVAudioSessionCategoryPlayAndRecord, withOptions: .AllowBluetooth)
    try audioSession.setActive(true)
}
catch let e
{
    debugPrint("failed to initialize audio session: \\(e)")
}

    + (NSString *) demonstrateInputSelection
{
    NSError* theError = nil;
    BOOL result = YES;
    NSMutableString *info = [[NSMutableString alloc] init];
    [info appendString: @"     Device Audio Input Hardware\
"];

    NSString *str = nil;
    if( iOSMajorVersion < 7 ){
        str = @"No input device information available";
        NSLog(@"%@",str);
        [info appendFormat:@"%@\
",str];

        return info;
    }

    AVAudioSession* myAudioSession = [AVAudioSession sharedInstance];

    result = [myAudioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:&theError];
    if (!result)
    {
        NSLog(@"setCategory failed");
    }

    result = [myAudioSession setActive:YES error:&theError];
    if (!result)
    {
        NSLog(@"setActive failed");
    }

    // Get the set of available inputs. If there are no audio accessories attached, there will be
    // only one available input -- the built in microphone.
    NSArray* inputs = [myAudioSession availableInputs];
    str = [NSString stringWithFormat:@"\
--- Ports available on %@: %d ---", [UIDevice currentDevice].name , [inputs count]];
    NSLog(@"%@",str);
    [info appendFormat:@"%@\
",str];

    // Locate the Port corresponding to the built-in microphone.
    AVAudioSessionPortDescription* builtInMicPort = nil;
    AVAudioSessionDataSourceDescription* frontDataSource = nil;

    for (AVAudioSessionPortDescription* port in inputs)
    {
        // Print out a description of the data sources for the built-in microphone
        str = @"\
**********";
        NSLog(@"%@",str);
        [info appendFormat:@"%@\
",str];
        str = [NSString stringWithFormat:@"Port :\"%@\": UID:%@", port.portName, port.UID ];
        NSLog(@"%@",str);
        [info appendFormat:@"%@\
",str];
        if( [port.dataSources count] ){
            str = [NSString stringWithFormat:@"Port has %d data sources",(unsigned)[port.dataSources count] ];
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }

        str = [NSString stringWithFormat:@">%@", port.dataSources];
        NSLog(@"%@",str);
   //     [info appendFormat:@"%@\
",str];

        if( [port.portType isEqualToString:AVAudioSessionPortLineIn] ){
            str = @"Line Input found";
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }
        else if( [port.portType isEqualToString:AVAudioSessionPortUSBAudio] ){
            str = @"USB Audio found";
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }
        else if ([port.portType isEqualToString:AVAudioSessionPortBuiltInMic]){
            builtInMicPort = port;
            str = @"Built-in Mic found";
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }
        else if ([port.portType isEqualToString:AVAudioSessionPortHeadsetMic]){
            builtInMicPort = port;
            str = @"Headset Mic found";
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }
        else{
            str = @"Other input source found";
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }

        // loop over the built-in mic's data sources and attempt to locate the front microphone
        for (AVAudioSessionDataSourceDescription* source in port.dataSources)
        {
            str = [NSString stringWithFormat:@"\
Name:%@ (%d) \
Polar:%@ \
Type:%@ \
Patterns:%@", source.dataSourceName, [source.dataSourceID intValue], source.selectedPolarPattern, port.portType, source.supportedPolarPatterns];
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];

            //           if ([source.orientation isEqual:AVAudioSessionOrientationFront])
            //           {
            //               frontDataSource = source;
            //               break;
            //           }
        } // end data source iteration

    }

    str = @"\
----  Current Selected Ports ----\
";
    NSLog(@"%@",str);
    [info appendFormat:@"%@",str];

    NSArray *currentInputs = myAudioSession.currentRoute.inputs;
//    str = [NSString stringWithFormat:@"\
%d current input ports", [currentInputs count]];
//    NSLog(@"%@",str);
//    [info appendFormat:@"%@\
",str];
    for( AVAudioSessionPortDescription *port in currentInputs ){
        str = [NSString stringWithFormat:@"\
Input Port :\"%@\":", port.portName ];
        NSLog(@"%@",str);
        [info appendFormat:@"%@\
",str];
        if( [port.dataSources count] ){
            str = [NSString stringWithFormat:@"Port has %d data sources",(unsigned)[port.dataSources count] ];
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];

            str = [NSString stringWithFormat:@"Selected data source:%@",  port.selectedDataSource.dataSourceName];
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];

            if( [port.selectedDataSource.supportedPolarPatterns count] > 0 ){
                str = [NSString stringWithFormat:@"Selected polar pattern:%@", port.selectedDataSource.selectedPolarPattern];
                NSLog(@"%@",str);
                [info appendFormat:@"%@\
",str];
            }
        }
    }

    NSArray *currentOutputs = myAudioSession.currentRoute.outputs;
//    str = [NSString stringWithFormat:@"\
%d current output ports", [currentOutputs count]];
//    NSLog(@"%@",str);
//    [info appendFormat:@"%@\
",str];
    for( AVAudioSessionPortDescription *port in currentOutputs ){
        str = [NSString stringWithFormat:@"\
Output Port :\"%@\":", port.portName ];
        NSLog(@"%@",str);
        [info appendFormat:@"%@\
",str];
        if( [port.dataSources count] ){
            str = [NSString stringWithFormat:@"Port has %d data sources",(unsigned)[port.dataSources count] ];
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];

            str = [NSString stringWithFormat:@"Selected data source:%@",  port.selectedDataSource.dataSourceName];
            NSLog(@"%@",str);
            [info appendFormat:@"%@\
",str];
        }

    }

//    str = [NSString stringWithFormat:@"\\Current Route: %@ Source:%@\
", myAudioSession.currentRoute.portName, myAudioSession.preferredInput.selectedDataSource.dataSourceName];
//    NSLog(@"%@",str);
//    [info appendFormat:@"%@\
",str];


    if( myAudioSession.preferredInput.portName ){
        str = [NSString stringWithFormat:@"\
Preferred Port: %@ Source:%@\
", myAudioSession.preferredInput.portName, myAudioSession.preferredInput.selectedDataSource.dataSourceName];
    } else {
        str = @"\
No Preferred Port set";
    }
    NSLog(@"%@",str);
    [info appendFormat:@"%@\
",str];

    return info;

    if (frontDataSource)
    {
        NSLog(@"Currently selected source is \"%@\" for port \"%@\"", builtInMicPort.selectedDataSource.dataSourceName, builtInMicPort.portName);
        NSLog(@"Attempting to select source \"%@\" on port \"%@\"", frontDataSource, builtInMicPort.portName);

        // Set a preference for the front data source.
        theError = nil;
        result = [builtInMicPort setPreferredDataSource:frontDataSource error:&theError];
        if (!result)
        {
            // an error occurred. Handle it!
            NSLog(@"setPreferredDataSource failed");
        }
    }

    // Make sure the built-in mic is selected for input. This will be a no-op if the built-in mic is
    // already the current input Port.
    theError = nil;
    result = [myAudioSession setPreferredInput:builtInMicPort error:&theError];
    if (!result)
    {
        // an error occurred. Handle it!
        NSLog(@"setPreferredInput failed");
    }

    return info;
}

AVAudioSessionRouteDescription *currentRoute = [[AVAudioSession sharedInstance] currentRoute];
    for (AVAudioSessionPortDescription *output in currentRoute.outputs) {

    }

extension AVAudioSession {
   
    @objc func ChangeAudioOutput(_ presenterViewController : UIViewController, _ speakerButton: UIButton) {
       
        let CHECKED_KEY ="checked"
        var deviceAction = UIAlertAction()
        var headphonesExist = false
       
        if AudioOutputDeviceHandler.sharedInstance.isDeviceListRequired() {
           
            let optionMenu = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
           
            for audioPort in self.availableInputs!{
               
                switch audioPort.portType {
                   
                case AVAudioSession.Port.bluetoothA2DP, AVAudioSession.Port.bluetoothHFP, AVAudioSession.Port.bluetoothLE :
                   
                    overrideBluetooth(audioPort, optionMenu)
                    break
                   
                case AVAudioSession.Port.builtInMic, AVAudioSession.Port.builtInReceiver:
                   
                    deviceAction = overrideBuiltInReceiver(audioPort)
                    break
                   
                case AVAudioSession.Port.headphones, AVAudioSession.Port.headsetMic:
                   
                    headphonesExist = true
                    overrideheadphones(audioPort,optionMenu)
                    break
                   
                case AVAudioSession.Port.carAudio:
                    overrideCarAudio(port: audioPort, optionMenu: optionMenu)
                    break
                   
                default:
                    break
                }
            }
           
            if !headphonesExist {
               
                if self.currentRoute.outputs.contains(where: {return $0.portType == AVAudioSession.Port.builtInReceiver}) || self.currentRoute.outputs.contains(where: {return $0.portType == AVAudioSession.Port.builtInMic}) {
                    deviceAction.setValue(true, forKey: CHECKED_KEY)
                }
                optionMenu.addAction(deviceAction)
            }
           
            overrideSpeaker(optionMenu)
           
            let cancelAction = UIAlertAction(title:"Cancel", style: .cancel, handler: {
                (alert: UIAlertAction!) -> Void in
               
            })
           
            optionMenu.addAction(cancelAction)
           
            alertViewSetupForIpad(optionMenu, speakerButton)
            presenterViewController.present(optionMenu, animated: false, completion: nil)
           
            // auto dismiss after 5 seconds
            DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) {
                optionMenu.dismiss(animated: true, completion: nil)
            }
           
        } else {
            if self.isBuiltInSpeaker {
               
                if AudioOutputDeviceHandler.sharedInstance.isSpeaker {
                    let port = self.currentRoute.inputs.first!
                    setPortToNone(port)
                    AudioOutputDeviceHandler.sharedInstance.isSpeaker = false
                }
            }
            else if self.isReceiver || self.isBuiltInMic  || self.isHeadphonesConnected {
               
                setPortToSpeaker()
                AudioOutputDeviceHandler.sharedInstance.isSpeaker = true
            }
        }
    }
   
    func overrideCarAudio(port: AVAudioSessionPortDescription, optionMenu: UIAlertController) {
       
        let action = UIAlertAction(title: port.portName, style: .default) { (action) in
            do {
                // set new input
                try self.setPreferredInput(port)
            } catch let error as NSError {
                print("audioSession error change to input: \\(port.portName) with error: \\(error.localizedDescription)")
            }
        }
       
        if self.currentRoute.outputs.contains(where: {return $0.portType == port.portType}){
            action.setValue(true, forKey:"checked")
        }
       
        if let image = UIImage(named:"CarAudio") {
            action.setValue(image, forKey:"image")
        }
        optionMenu.addAction(action)
    }
   
    func overrideheadphones(_ port: AVAudioSessionPortDescription, _ optionMenu: UIAlertController) {
       
        let CHECKED_KEY ="checked"
        let HEADPHONES_TITLE ="Headphones"
        let action = UIAlertAction(title: HEADPHONES_TITLE, style: .default) { (action) in
            do {
                // set new input
                try self.setPreferredInput(port)
            } catch let error as NSError {
                print("audioSession error change to input: \\(port.portName) with error: \\(error.localizedDescription)")
            }
        }
       
        if self.currentRoute.outputs.contains(where: {return $0.portType == AVAudioSession.Port.headphones}) || self.currentRoute.outputs.contains(where: {return $0.portType == AVAudioSession.Port.headsetMic}) {
            action.setValue(true, forKey: CHECKED_KEY)
        }
       
        if let image = UIImage(named:"Headphone") {
            action.setValue(image, forKey:"image")
        }
       
        optionMenu.addAction(action)
    }
   
    func overrideSpeaker(_ optionMenu: UIAlertController) {
       
        let SPEAKER_TITLE ="Speaker"
        let CHECKED_KEY ="checked"
        let speakerOutput = UIAlertAction(title: SPEAKER_TITLE, style: .default, handler: {
            [weak self] (alert: UIAlertAction!) -> Void in
            self?.setPortToSpeaker()
        })
        AudioOutputDeviceHandler.sharedInstance.isSpeaker = true
       
        if self.currentRoute.outputs.contains(where: {return $0.portType == AVAudioSession.Port.builtInSpeaker}){
           
            speakerOutput.setValue(true, forKey: CHECKED_KEY)
        }
       
        if let image = UIImage(named:"Speaker") {
            speakerOutput.setValue(image, forKey:"image")
        }
        optionMenu.addAction(speakerOutput)
    }
   
    func overrideBluetooth(_ port: AVAudioSessionPortDescription, _ optionMenu: UIAlertController) {
       
        let CHECKED_KEY ="checked"
        let action = UIAlertAction(title: port.portName, style: .default) { (action) in
            do {
                // set new input
                try self.setPreferredInput(port)
            } catch let error as NSError {
                print("audioSession error change to input: \\(port.portName) with error: \\(error.localizedDescription)")
            }
        }
       
        if self.currentRoute.outputs.contains(where: {return $0.portType == port.portType}){
            action.setValue(true, forKey: CHECKED_KEY)
        }
        if let image = UIImage(named:"Bluetooth") {
            action.setValue(image, forKey:"image")
        }
        optionMenu.addAction(action)
    }
   
    func overrideBuiltInReceiver(_ port: AVAudioSessionPortDescription) -> UIAlertAction {
       
        let IPHONE_TITLE ="iPhone"
        let deviceAction = UIAlertAction(title: IPHONE_TITLE, style: .default) {[weak self] (action) in
            self?.setPortToNone(port)
        }
       
        if let image = UIImage(named:"Device") {
            deviceAction.setValue(image, forKey:"image")
        }
        return deviceAction
    }
   
    func setPortToSpeaker() {
       
        do {
            try self.overrideOutputAudioPort(AVAudioSession.PortOverride.speaker)
        } catch let error as NSError {
            print("audioSession error turning on speaker: \\(error.localizedDescription)")
        }
    }
   
    func setPortToNone(_ port: AVAudioSessionPortDescription) {
       
        do {
            // remove speaker if needed
            try self.overrideOutputAudioPort(AVAudioSession.PortOverride.none)
            // set new input
            try self.setPreferredInput(port)
        } catch let error as NSError {
            print("audioSession error change to input: \\(AVAudioSession.PortOverride.none.rawValue) with error: \\(error.localizedDescription)")
        }
    }
   
    func alertViewSetupForIpad(_ optionMenu: UIAlertController, _ speakerButton: UIButton) {
        optionMenu.modalPresentationStyle = .popover
        if let presenter = optionMenu.popoverPresentationController {
            presenter.sourceView = speakerButton;
            presenter.sourceRect = speakerButton.bounds;
        }
    }
}

extension AVAudioSession {
   
    static var isHeadphonesConnected: Bool {
        return sharedInstance().isHeadphonesConnected
    }
   
    static var isBluetoothConnected: Bool {
        return sharedInstance().isBluetoothConnected
    }
   
    static var isCarAudioConnected: Bool {
        return sharedInstance().isCarAudioConnected
    }
   
    static var isBuiltInSpeaker: Bool {
        return sharedInstance().isBuiltInSpeaker
    }
   
    static var isReceiver: Bool {
        return sharedInstance().isReceiver
    }
   
    static var isBuiltInMic: Bool {
        return sharedInstance().isBuiltInMic
    }
   
    var isCarAudioConnected: Bool {
        return !currentRoute.outputs.filter { $0.isCarAudio }.isEmpty
    }
   
    var isHeadphonesConnected: Bool {
        return !currentRoute.outputs.filter { $0.isHeadphones }.isEmpty
    }
   
    var isBluetoothConnected: Bool {
        return !currentRoute.outputs.filter { $0.isBluetooth }.isEmpty
    }
   
    var isBuiltInSpeaker: Bool {
        return !currentRoute.outputs.filter { $0.isSpeaker }.isEmpty
    }
   
    var isReceiver: Bool {
        return !currentRoute.outputs.filter { $0.isReceiver }.isEmpty
    }
   
    var isBuiltInMic: Bool {
        return !currentRoute.outputs.filter { $0.isBuiltInMic }.isEmpty
    }
}

extension AVAudioSessionPortDescription {
   
    var isHeadphones: Bool {
        return portType == AVAudioSession.Port.headphones  ||  portType == AVAudioSession.Port.headsetMic
    }
   
    var isBluetooth: Bool {
        return portType == AVAudioSession.Port.bluetoothHFP || portType == AVAudioSession.Port.bluetoothA2DP || portType == AVAudioSession.Port.bluetoothLE
    }
   
    var isCarAudio: Bool {
        return portType == AVAudioSession.Port.carAudio
    }
   
    var isSpeaker: Bool {
        return portType == AVAudioSession.Port.builtInSpeaker
    }
   
    var isBuiltInMic: Bool {
        return portType == AVAudioSession.Port.builtInMic
    }
   
    var isReceiver: Bool {
        return portType == AVAudioSession.Port.builtInReceiver
    }
}