ios - CoreMotion 无法在 Swift Playgrounds 中工作

Question

import UIKit
import ARKit
import PlaygroundSupport
import SceneKit
import CoreMotion

class MyViewController: UIViewController {

let motionManager = CMMotionManager()
var timer: Timer!
var label = UILabel(frame: CGRect(x: 50, y: 400, width: 400, height: 100))

override func loadView() {

    let view = UIView()

    view.addSubview(label)
    label.text = "Show Yaw Here"
    self.view = view
    view.backgroundColor = .white

    motionManager.startAccelerometerUpdates()
    motionManager.startGyroUpdates()
    motionManager.startMagnetometerUpdates()
    motionManager.startDeviceMotionUpdates()

    timer = Timer.scheduledTimer(timeInterval: 0.2, target: self, selector: #selector(MyViewController.update), userInfo: nil, repeats: true)
}

@objc func update() {
    self.label.text = "Obama"
    if let accelerometerData = motionManager.accelerometerData {
        print("Device Accelerometer: \(accelerometerData)")
    }
    if let gyroData = motionManager.gyroData {
        print("Device Gyro: \(gyroData)")
    }
    if let magnetometerData = motionManager.magnetometerData {
        print("Device Magnetometer: \(magnetometerData)")
    }
    if let deviceMotion = motionManager.deviceMotion {
        print("Device Motion: \(deviceMotion)")
        let yaw = (Int)(Double(floor(1000*deviceMotion.attitude.yaw)/1000) * 180.0/Double.pi)
        self.label.text = "Yaw: \(yaw) Degrees"
    }
}
}
PlaygroundPage.current.liveView = MyViewController()

这(上面)是我用作 Playground 的代码。我直接从 iOS 应用程序获取代码，当我在同一设备(即 2018 年初运行 iOS 12 的 iPad)上运行 iOS 应用程序时，它可以完美运行。这是我用于实际应用程序的代码，它可以在iPad。它所做的只是将偏航值(以度为单位)写入文本框。当我运行它们中的任何一个时，我都没有收到错误或警告。 View Controller 确实显示在 Playground 中，初始标签文本也显示在 Playground 中，但是当我移动 iPad 时，代码不会更新设备运动，而它会在应用版本中更新。

import UIKit
import CoreMotion

class ViewController: UIViewController {

let motionManager = CMMotionManager()
var timer: Timer!
@IBOutlet weak var label: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()

    label.text = "ayy lmao"

    motionManager.startAccelerometerUpdates()
    motionManager.startGyroUpdates()
    motionManager.startMagnetometerUpdates()
    motionManager.startDeviceMotionUpdates()

    timer = Timer.scheduledTimer(timeInterval: 0.2, target: self, selector: #selector(ViewController.update), userInfo: nil, repeats: true)
}

@objc func update() {
    if let accelerometerData = motionManager.accelerometerData {
        print("Device Accelerometer: \(accelerometerData)")
    }
    if let gyroData = motionManager.gyroData {
        print("Device Gyro: \(gyroData)")
    }
    if let magnetometerData = motionManager.magnetometerData {
        print("Device Magnetometer: \(magnetometerData)")
    }
    if let deviceMotion = motionManager.deviceMotion {
        print("Device Motion: \(deviceMotion)")
        let yaw = (Int)(deviceMotion.attitude.yaw * 180.0/Double.pi)
        self.label.text = "Yaw: \(yaw) Degrees"
    }
}
}

Answer 1

核心位置 API 是异步的，因此您必须在调用 startUpdatingLocation() 后保持 Playground 运行。所以尝试一下

PlaygroundPage.current.needsIndefiniteExecution = true 

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