Вземете System Volume iOS

Актуализация за Swift

let vol = AVAudioSession.sharedInstance().outputVolume

Аудио сесията може да осигури изходен обем (iOS ›= 6.0).

float vol = [[AVAudioSession sharedInstance] outputVolume];
NSLog(@"output volume: %1.2f dB", 20.f*log10f(vol+FLT_MIN));

Swift 3.1

let audioSession = AVAudioSession.sharedInstance()
var volume: Float?
do {
    try audioSession.setActive(true)
    volume = audioSession.outputVolume
} catch {
    print("Error Setting Up Audio Session")
}

audioSession.setActive(true) - важно

Опитайте тази:

MPMusicPlayerController *iPod = [MPMusicPlayerController iPodMusicPlayer];
float volumeLevel = iPod.volume;

Трябва да импортирате рамката на MediaPlayer.

Това работи добре:

Float32 volume;
UInt32 dataSize = sizeof(Float32);

AudioSessionGetProperty (
                     kAudioSessionProperty_CurrentHardwareOutputVolume,
                     &dataSize,
                     &volume
                     );

За Swift 2:

let volume = AVAudioSession.sharedInstance().outputVolume   
print("Output volume: \(volume)")

Можете да използвате обема на системата по подразбиране View и да добавяте, където имате нужда. В моя случай го изисквах в собствения си музикален плейър. Това е лесно и безпроблемно. Просто добавете изгледа и всичко е готово. Това е обяснено в Справочник за клас MPVolume.

mpVolumeViewParentView.backgroundColor = [UIColor clearColor];
MPVolumeView *myVolumeView =
[[MPVolumeView alloc] initWithFrame: mpVolumeViewParentView.bounds];
[mpVolumeViewParentView addSubview: myVolumeView];
[myVolumeView release];

Подготвил съм клас със статични методи, за да се справя с обема на ios устройства. Нека споделя с вас :)

import AVFoundation
class HeadPhoneDetectHelper {
class func isHeadPhoneConnected() -> Bool
{
    do{
        let audioSession = AVAudioSession.sharedInstance()
        try audioSession.setActive(true)
        let currentRoute = audioSession.currentRoute
        let headPhonePortDescriptionArray = currentRoute.outputs.filter{$0.portType == AVAudioSessionPortHeadphones}
        let isHeadPhoneConnected = headPhonePortDescriptionArray.count != 0
        return isHeadPhoneConnected
    }catch{
        print("Error while checking head phone connection : \(error)")
    }
    return false
}

class func isVolumeLevelAppropriate() -> Bool
{
    let minimumVolumeLevelToAccept = 100
    let currentVolumeLevel = HeadPhoneDetectHelper.getVolumeLevelAsPercentage()
    let isVolumeLevelAppropriate = currentVolumeLevel >= minimumVolumeLevelToAccept
    return isVolumeLevelAppropriate
}

class func getVolumeLevelAsPercentage() -> Int
{
    do{
        let audioSession = AVAudioSession.sharedInstance()
        try audioSession.setActive(true)
        let audioVolume =  audioSession.outputVolume
        let audioVolumePercentage = audioVolume * 100
        return Int(audioVolumePercentage)
    }catch{
        print("Error while getting volume level \(error)")
    }
    return 0
}
}

Swift 2.2, не забравяйте да импортирате MediaPlayer

private func setupVolumeListener()
{
    let frameView:CGRect = CGRectMake(0, 0, 0, 0)
    let volumeView = MPVolumeView(frame: frameView)
    //self.window?.addSubview(volumeView) //use in app delegate
   self.view.addSubview(volumeView)  //use in a view controller


    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(volumeChanged(_:)), name: "AVSystemController_SystemVolumeDidChangeNotification", object: nil)
}//eom



func volumeChanged(notification:NSNotification)
{
    let volume = notification.userInfo!["AVSystemController_AudioVolumeNotificationParameter"]
    let category = notification.userInfo!["AVSystemController_AudioCategoryNotificationParameter"]
    let reason = notification.userInfo!["AVSystemController_AudioVolumeChangeReasonNotificationParameter"]

    print("volume:      \(volume!)")
    print("category:    \(category!)")
    print("reason:      \(reason!)")
    print("\n")
}//eom