app在后台可以震动

1. app开启后台运行权限，定位或者录音等都可以
2. 设置AVAudioSession时，mode设置为voiceChat
3. 手机震动调用
   AudioServicesPlaySystemSoundWithCompletion(kSystemSoundID_Vibrate, nil)

import UIKit
import AVFoundation

class ViewController: UIViewController {

    var recorder: AVAudioRecorder?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let session = AVAudioSession.sharedInstance()
        try? session.setCategory(.playAndRecord, mode: .voiceChat, options: [])
        try? session.setActive(true)
        
        /**
         AVAudioSession.category = playAndRecord
         mode = defualt, 震动不生效
         mode = voiceChat, 可以震动
         */
        let url = URL(fileURLWithPath: NSTemporaryDirectory().appending("/abc.caf"))
        recorder = try? AVAudioRecorder(url: url, settings: [:])
        recorder?.prepareToRecord()
        recorder?.record()
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        Timer.scheduledTimer(withTimeInterval: 3, repeats: true) { _ in
            AudioServicesPlaySystemSoundWithCompletion(1521, nil)
            //AudioServicesPlaySystemSoundWithCompletion(kSystemSoundID_Vibrate, nil)
        }
    }
}