高校课程项目：Swift获取iPhone用户音量设置的合法方法问询

Hey there! Awesome to hear about your college project's shake-controlled audio feature—super creative idea, and kudos for being mindful of respecting user settings (that's such an important best practice).

To directly answer your question: Yes, there's a straightforward, compliant way to get the user's system volume setting in Swift using AVAudioSession. The key here is the outputVolume property, which is read-only (perfect for your use case since you don't want to modify anything).

How to Fetch the System Volume #

Here's a simple function to retrieve the current system volume (returns a value between 0.0 and 1.0, corresponding to 0% to 100% volume):

import AVFoundation

func getCurrentSystemVolume() -> Float {
    do {
        let audioSession = AVAudioSession.sharedInstance()
        // Activate the session temporarily (needed in some cases to access outputVolume)
        try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
        let volume = audioSession.outputVolume
        // Deactivate the session if you don't need it active anymore
        try audioSession.setActive(false)
        return volume
    } catch {
        print("Failed to access audio session: \(error.localizedDescription)")
        return 0.0
    }
}

Bonus: Listen for Volume Changes #

If you want to keep your app's reference to the system volume up-to-date (in case the user adjusts it manually via the side buttons or Control Center), you can listen for the outputVolumeDidChangeNotification:

// Add this in your view controller's init or viewDidLoad
override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(systemVolumeDidChange(_:)),
        name: AVAudioSession.outputVolumeDidChangeNotification,
        object: nil
    )
}

// Handle the volume change notification
@objc private func systemVolumeDidChange(_ notification: Notification) {
    guard let newVolume = notification.userInfo?[AVAudioSessionOutputVolumeKey] as? Float else {
        return
    }
    print("System volume updated to: \(newVolume)")
    // Update your app's volume reference here
}

// Don't forget to remove the observer when your view controller is deallocated
deinit {
    NotificationCenter.default.removeObserver(self)
}

Important Notes #

• Compliance: This approach is 100% allowed by Apple's guidelines. Since you're only reading a read-only property and not modifying any system settings, you won't run into any issues with app store approval.
• Permissions: You don't need any special privacy permissions (like microphone access) to use this—AVAudioSession access for reading output volume is unrestricted.

This should give you the baseline volume value you need to scale based on the shake intensity/speed your app already detects. Have fun building that feature! 🎧

内容的提问来源于stack exchange，提问作者Cody Berry