Question

试图弄清楚如何读取Apple耳机的音量按钮以用作相机快门的触发器（如Apple Camera应用程序那样）。

从Remote Control Events， Remote Control Received With Event和this git repo上的文档中，我拼凑起来，我可能需要AVAudioPlayer个对象，.beginReceivingRemoteControlEvents()和remoteControlReceivedWithEvent，以及发表此观点canBecomeFirstResponder() return true。

import UIKit
import AVFoundation

class ViewController: UIViewController, AVAudioPlayerDelegate {
    var player: AVAudioPlayer!
    override func viewDidLoad() {
        super.viewDidLoad()

        var session: AVAudioSession = AVAudioSession.sharedInstance()
        session.setActive(true, error: nil)
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        println("viewDidAppear worked...")
        self.becomeFirstResponder()
        UIApplication.sharedApplication().beginReceivingRemoteControlEvents()
    }

    override func canBecomeFirstResponder() -> Bool {
        return true
    }

    override func remoteControlReceivedWithEvent(event: UIEvent) {
        let rc = event.subtype
        println("does this work? \(rc.rawValue)")
        //takePicture()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

我希望在按下耳机上的音量按钮时获得"does this work"，而我只是看到它正常调整耳机音量。所以我必须遗漏一些东西，可能是delegate或AVSession？

Answer 1

我在r/swift上交叉发布了这个，我被告知它可能需要播放音频（直接从文档中引用）。

因此，虽然这不是理想的解决方案，但它适用于我自己的私人用途。

import UIKit
import AVFoundation
import MediaPlayer

class ViewController: UIViewController, AVAudioPlayerDelegate {
    var testPlayer: AVAudioPlayer? = nil

    func loadSound(filename: NSString) -> AVAudioPlayer {
        let url = NSBundle.mainBundle().URLForResource(filename as String, withExtension: "caf")
        var error: NSError? = nil
        let player = AVAudioPlayer(contentsOfURL: url, error: &error)
        if error != nil {
            println("Error loading \(url): \(error?.localizedDescription)")
        } else {
            player.prepareToPlay()
        }
        return player
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        self.testPlayer = self.loadSound("silence")
        self.testPlayer?.numberOfLoops = -1
        self.testPlayer?.play()
    }

    override func canBecomeFirstResponder() -> Bool {
        return true
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        self.becomeFirstResponder()
        UIApplication.sharedApplication().beginReceivingRemoteControlEvents()
    }

    override func remoteControlReceivedWithEvent(event: UIEvent) {
        let rc = event.subtype
        println("rc.rawValue: \(rc.rawValue)")
        // take photo
    }
}

我注意到在Apple的相机应用程序中，+ / - 音量按钮会触发相机，而麦克风按钮会暂停/播放在另一个应用程序中运行的任何音频，但在此实现中，音量按钮仍可控制音量（以及任何音频）应用程序启动时已暂停。

rc.rawValue: 103对应麦克风按钮的单击，双击返回104，三击返回105，然后有时会碰到一对夫妇返回108或109。

Answer 2

基于Cody的答案，但已于2019年更新（Swift 5）

-O

使用Swift

2 个答案: