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

Question

我在Xcode 9 beta,iOS 11中使用谷歌地图.

我收到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: - [UIApplication applicationState] PID:4442,TID:837820,线程名称:com.google.Maps.LabelingBehavior,队列名称: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并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)")
        }
    }

Answer 1

很难找到有时没有在主线程中执行的UI代码.您可以使用以下技巧找到并修复它.

1. 选择编辑方案 - >诊断,勾选主线程检查器和暂停问题.

2. 运行iOS应用程序以重现此问题.(Xcode应该在第一个问题上暂停.)

3. 包含修改UI的代码 DispatchQueue.main.async {}

Answer 2

尝试包装修改UI的所有代码行DispatchQueue.main.async {}.

Answer 3

首先，请确保使用以下方法从主线程中调用Google地图和ui更改的调用：

DispatchQueue.main.async {
    //Do UI Code here. 
    //Call Google maps methods.
}

另外，更新您当前版本的Google地图。Google地图必须对线程检查器进行一些更新。

问题是：“为什么会这样？” 我认为苹果为一个边缘案例添加了一个断言，然后谷歌不得不为其更新pod。