Swift Gyroscope: Неожиданно найдено нуль при разворачивании необязательного значения

Question

Я работаю с Core Motion, и я получаю «Неожиданно найдено нуль при распаковке необязательного значения», но только около половины времени загрузки приложения. Как исправить приведенный ниже код, так что он стабилен?

import UIKit 
import CoreMotion 

class ViewController: UIViewController { 

var currentMaxRotX: Double = 0.0 
var currentMaxRotY: Double = 0.0 
var currentMaxRotZ: Double = 0.0 

let motionManager = CMMotionManager() 

@IBOutlet var RollLabel: UILabel! 
@IBOutlet var PitchLabel: UILabel! 
@IBOutlet var YawLabel: UILabel! 

@IBOutlet var rotX: UILabel! 
@IBOutlet var rotY: UILabel! 
@IBOutlet var rotZ: UILabel! 

@IBOutlet var maxRotX: UILabel! 
@IBOutlet var maxRotY: UILabel! 
@IBOutlet var maxRotZ: UILabel! 


@IBOutlet var readOutLabel: UILabel! 

override func viewDidLoad() { 

    if motionManager.gyroAvailable { 

     motionManager.startGyroUpdates() 
     motionManager.deviceMotionUpdateInterval = 0.2 
     motionManager.startDeviceMotionUpdates() 

     motionManager.gyroUpdateInterval = 0.2 
     motionManager.startGyroUpdatesToQueue(NSOperationQueue.currentQueue()) { 
      [weak self] (gyroData: CMGyroData!, error: NSError!) in 

      if self?.outputRotationData(gyroData.rotationRate) != nil { 

      self?.outputRotationData(gyroData.rotationRate) 
      if error != nil { 
       println("\(error)") 
      } 

     } 
     } 

    } else { 
     println("gyro not avail") 
    } 

    super.viewDidLoad() 
} 
// radians to degrees 
func radians(fromDegrees degrees: Double) -> Double { 
    return 180 * degrees/M_PI 
} 

func outputRotationData(rotation:CMRotationRate) 
{ 
    rotX.text = NSString(format:"Rotation X: %.4f",rotation.x) as String 
    if fabs(rotation.x) > fabs(currentMaxRotX) 
    { 
     currentMaxRotX = rotation.x 
    } 

    rotY.text = NSString(format:"Rotation Y: %.4f", rotation.y) as String 
    if fabs(rotation.y) > fabs(currentMaxRotY) 
    { 
     currentMaxRotY = rotation.y 
    } 
    rotZ.text = NSString(format:"Rotation Z:%.4f", rotation.z) as String 
    if fabs(rotation.z) > fabs(currentMaxRotZ) 
    { 
     currentMaxRotZ = rotation.z 
    } 

    maxRotX.text = NSString(format:"Max rotation X: %.4f", currentMaxRotX) as String 
    maxRotY.text = NSString(format:"Max rotation Y:%.4f", currentMaxRotY) as String 
    maxRotZ.text = NSString(format:"Max rotation Z:%.4f", currentMaxRotZ) as String 

    var attitude = CMAttitude() 
    var motion = CMDeviceMotion() 
    motion = motionManager.deviceMotion 
    attitude = motion.attitude 


    YawLabel.text = NSString (format: "Yaw: %.2f", attitude.yaw) as String 
    PitchLabel.text = NSString (format: "Pitch: %.2f", attitude.pitch) as String 
    RollLabel.text = NSString (format: "Roll: %.2f", attitude.roll) as String 

    if NSString(string: RollLabel.text!).doubleValue <= -1.6 && NSString(string: RollLabel.text!).doubleValue >= -1.2 { 
     readOutLabel.text = "" 
    } 
    else{ 
     readOutLabel.text = "" 
    } 

} 
} 

Answer 1

Я понял это:

var attitude = CMAttitude() 
var motion = CMDeviceMotion() 

if motionManager.deviceMotion != nil{ 
    motion = motionManager.deviceMotion 
    attitude = motion.attitude 
    YawLabel.text = NSString (format: "Yaw: %.2f", attitude.yaw) as String 
    PitchLabel.text = NSString (format: "Pitch: %.2f", attitude.pitch) as String 
    RollLabel.text = NSString (format: "Roll: %.2f", attitude.roll) as String 
}