Switching audio output between Receiver and Speaker in iOS7 and above?

I have an audio player which has an option of switching the Audio Output from Speaker to Receiver/Earpiece (irrespective of whether headset is connected) when proximity sensor notifies 1. The following is my code for doing so.

- (void) switchAudioOutput:(NSString*)output{
    AVAudioSession* audioSession = [AVAudioSession sharedInstance];
    BOOL success;
    NSError* error;

    if([output isEqualToString:keAudioOutputReciever]){
        //Force current audio out through reciever
        //set the audioSession override
        success = [audioSession overrideOutputAudioPort:AVAudioSessionPortOverrideNone
                                             error:&error];
        if (!success)
            NSLog(@"AVAudioSession error overrideOutputAudioPort:%@",error);

        //activate the audio session
        success = [audioSession setActive:YES error:&error];
        if (!success)
            NSLog(@"AVAudioSession error activating: %@",error);
        else
            NSLog(@"AVAudioSession active with override: AVAudioSessionPortOverrideNone");

    }else if([output isEqualToString:keAudioOutputSpeaker]){
        //set the audioSession override
        success = [audioSession overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker
                                                  error:&error];
        if (!success)
            NSLog(@"AVAudioSession error overrideOutputAudioPort:%@",error);

        //activate the audio session
        success = [audioSession setActive:YES error:&error];
        if (!success)
            NSLog(@"AVAudioSession error activating: %@",error);
        else
            NSLog(@"AVAudioSession active with override: AVAudioSessionPortOverrideSpeaker");

    }
 }

This was based on the answer Toggle Button route audio to speaker and receiver and enter link description here. I noticed that this only forces the Audio to Speaker alone but does not ensure that the route goes to receiver alone. Moreover while shifting to speaker I get the following error:

AVAudioSession error overrideOutputAudioPort:Error Domain=NSOSStatusErrorDomain Code=-50 "The operation couldn’t be completed. (OSStatus error -50.)"

I figured out the answer by avoiding overrides for Receiver

- (void) setAudioSession:(NSString*)audioOutput{

        NSError* error;
        if([audioOutput isEqualToString:audioOutputSpeaker.lowercaseString]){

            //set the audioSession override
            if(![self setCategory:AVAudioSessionCategoryPlayAndRecord
                              withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker|AVAudioSessionCategoryOptionAllowBluetooth
                                    error:&error])
                NSLog(@"AVAudioSession error AVAudioSessionCategoryPlayAndRecord:%@",error);

            //activate the audio session
            if (![self setActive:YES error:&error])
                NSLog(@"AVAudioSession error activating: %@",error);
            else
                NSLog(@"AVAudioSession active with override: AVAudioSessionPortOverrideNone");
        }else if ([audioOutput isEqualToString:audioOutputReciever.lowercaseString]){
            //Force current audio out through reciever
            //set the audioSession override
            if(![self setCategory:AVAudioSessionCategoryPlayAndRecord
                              withOptions:AVAudioSessionCategoryOptionAllowBluetooth
                                    error:&error])
                NSLog(@"AVAudioSession error AVAudioSessionCategoryPlayAndRecord:%@",error);

            if (![self overrideOutputAudioPort:AVAudioSessionPortOverrideNone error:&error])
                NSLog(@"AVAudioSession error overrideOutputAudioPort to Reciever:%@",error);

            //activate the audio session
            if (![self setActive:YES error:&error])
                NSLog(@"AVAudioSession error activating: %@",error);
            else
                NSLog(@"AVAudioSession active with override: AVAudioSessionPortOverrideNone");
        }
    }