iPhone：iOS 17.4中没有气压数据

Note that the following is a work-around. I urge everybody to file a bug-report with Apple, to make sure there is pressure on Apple to fix this.个

首先，NSMotionUsageDescription键必须在应用程序的.info.plist文件中定义.

其他人则提出了CMSensorRecorder种变通办法.事实证明，设置应用程序中的"健身跟踪"设置需要启用才能工作.

当authorizationStatus为.restricted,时，用户首先需要打开设置>；"隐私和安全">；"运动和健身">；"健身跟踪".

当authorizationStatus是.notDetermined,时，则开始CMSensorRecorder.你的应用程序的设置中将添加"Motion&；Fitness"隐私设置，用户将被iOS要求授权.当用户接受时，authorizationStatus将更改为.authorized，您可以启动CMAltimeter.

当authorizationStatus为.denied,时，用户需要打开应用程序的"运动健身"隐私设置.&

以下代码对我有效:

let status = CMAltimeter.authorizationStatus()
switch status {
case .notDetermined:
    // trigger a authorization popup
    let recorder = CMSensorRecorder()
    DispatchQueue.global().async {
       recorder.recordAccelerometer(forDuration: 0.1)
    }
case .restricted:
    popupText = "Please switch \"Fitness Tracking\" on, in the Apple Settings app, under \"Privacy & Security\" > \"Motion & Fitness\""
    showingPopup = true
case .denied:
    popupText = "Please switch \"Motion & Fitness\" on, in the app settings"
    showingPopup = true
default:
    print("authorized")
}
Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { timer in
   let status = CMAltimeter.authorizationStatus()
   if status == .authorized {
      timer.invalidate()
      self.altimeter.startRelativeAltitudeUpdates(to: OperationQueue.main) { (data, _error) in
         // handle altimeter data
      }
   }
}