AVAudioSession.sharedInstance().outputVolume 未始终返回正确的音量

Question

使用下面的代码，我得到了输出音量，但它确实不一致 - 有时它给出相同的值，有时它是一个落后的音量变化，尽管系统音量实际上是正确变化的。

有什么办法让它每次都输出正确的值？

func viewDidLoad() {
...

        NotificationCenter.default.addObserver(self, selector: #selector(volumeDidChange), name: NSNotification.Name(rawValue: "AVSystemController_SystemVolumeDidChangeNotification"), object: nil)
...

}


func volumeDidChange() {
   print("VOLUME CHANGING", AVAudioSession.sharedInstance().outputVolume)

// output while changing the volume with hardware buttons
VOLUME CHANGING 0.0625
VOLUME CHANGING 0.0625
VOLUME CHANGING 0.125
VOLUME CHANGING 0.1875
VOLUME CHANGING 0.25
VOLUME CHANGING 0.375
VOLUME CHANGING 0.375
VOLUME CHANGING 0.4375
VOLUME CHANGING 0.5
VOLUME CHANGING 0.5625
VOLUME CHANGING 0.625
VOLUME CHANGING 0.6875
VOLUME CHANGING 0.75
VOLUME CHANGING 0.8125
VOLUME CHANGING 0.875
VOLUME CHANGING 0.75
VOLUME CHANGING 0.6875
VOLUME CHANGING 0.625
VOLUME CHANGING 0.625
VOLUME CHANGING 0.5625
VOLUME CHANGING 0.5
VOLUME CHANGING 0.4375
VOLUME CHANGING 0.375
VOLUME CHANGING 0.3125
VOLUME CHANGING 0.375
VOLUME CHANGING 0.4375
VOLUME CHANGING 0.4375

Answer 1

尝试

import AVFoundation
import MediaPlayer

//MARK: Did Load
override func viewDidLoad() {
    super.viewDidLoad()

    /// Volume View
    let volumeView = MPVolumeView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
    volumeView.isHidden = false
    volumeView.alpha = 0.01
    view.addSubview(volumeView)

    /// Notification Observer
     NotificationCenter.default.addObserver(self, selector: #selector(self.volumeDidChange(notification:)), name: NSNotification.Name(rawValue: "AVSystemController_SystemVolumeDidChangeNotification"), object: nil)
}

@objc func volumeDidChange(notification: NSNotification) {
    //print("VOLUME CHANGING", AVAudioSession.sharedInstance().outputVolume)

    let volume = notification.userInfo!["AVSystemController_AudioVolumeNotificationParameter"] as! Float
    print("Device Volume:\(volume)")
}

您当前的输出 - 重复相同的值

需要输出

Answer 2

更新为 Swift 4.2

override func viewDidLoad() {
    super.viewDidLoad()
    let session = AVAudioSession.sharedInstance()
    
    do {
        try session.setActive(true)
    } catch {
        print("error in getting volume")
    }
    
    if session.outputVolume < 1.0 {
        volumeButton = 0
    } else {
        volumeButton = 1
    }
    
    NotificationCenter.default.addObserver(self, selector: #selector(self.volumeDidChange(notification:)), name: NSNotification.Name(rawValue: "AVSystemController_SystemVolumeDidChangeNotification"), object: nil)
}

@objc func volumeDidChange(notification: NSNotification) {
    if let volume = notification.userInfo?["AVSystemController_AudioVolumeNotificationParameter"] as? Float{
        print("Device Volume:\(volume)")
    } else{
        print("Error while reading value...")
    }
}

AVAudioSession.sharedInstance().outputVolume 未始终返回正确的音量

AVAudioSession.sharedInstance().outputVolume Not Returning Correct Volume Consistently

ios

avaudiosession

swift

更新为 Swift 4.2