主线程检查器: 在后台线程上调用的 UI API:-[ UIApplicationapplicationState ]

我在 Xcode 9 beta，iOS 11中使用谷歌地图。

我得到一个错误输出到日志如下:

主线程检查器: 在后台线程上调用的 UI API:-[ UIApplicationapplicationState ] PID: 4442，TID: 837820，Thread name: com.google. Maps. LabelingBehavior，Queue name: com.apple.root.default-QoS. overcommit，QoS: 21

为什么会发生这种情况，因为我几乎可以肯定我没有改变代码中主线程的任何接口元素。

 override func viewDidLoad() {


let locationManager = CLLocationManager()




locationManager.requestAlwaysAuthorization()




locationManager.requestWhenInUseAuthorization()


if CLLocationManager.locationServicesEnabled() {


locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters
locationManager.startUpdatingLocation()
}


viewMap.delegate = self


let camera = GMSCameraPosition.camera(withLatitude: 53.7931183329367, longitude: -1.53649874031544, zoom: 17.0)




viewMap.animate(to: camera)




}


func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let locValue:CLLocationCoordinate2D = manager.location!.coordinate
print("locations = \(locValue.latitude) \(locValue.longitude)")
}


func mapView(_ mapView: GMSMapView, willMove gesture: Bool) {




}


func mapView(_ mapView: GMSMapView, idleAt position: GMSCameraPosition) {


if(moving > 1){
moving = 1
UIView.animate(withDuration: 0.5, delay: 0, animations: {


self.topBarConstraint.constant = self.topBarConstraint.constant + (self.topBar.bounds.height / 2)


self.bottomHalfConstraint.constant = self.bottomHalfConstraint.constant + (self.topBar.bounds.height / 2)


self.view.layoutIfNeeded()
}, completion: nil)
}
moving = 1
}




// Camera change Position this methods will call every time
func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) {
moving = moving + 1
if(moving == 2){




UIView.animate(withDuration: 0.5, delay: 0, animations: {




self.topBarConstraint.constant = self.topBarConstraint.constant - (self.topBar.bounds.height / 2)


self.bottomHalfConstraint.constant = self.bottomHalfConstraint.constant - (self.topBar.bounds.height / 2)




self.view.layoutIfNeeded()
}, completion: nil)
}
DispatchQueue.main.async {


print("Moving: \(moving) Latitude: \(self.viewMap.camera.target.latitude)")
print("Moving: \(moving)  Longitude: \(self.viewMap.camera.target.longitude)")
}
}