地理位置 - 如果我从启用 GPS 开始，Ionic 3 天气应用程序可以正常工作

Question

如果我从启用 GPS 开始，我的 Ionic 3 天气应用程序可以正常工作。

如果我在 GPS 关闭的情况下启动应用程序，并订阅收听更改（请参阅下面的 watch.subscribe），但手动启用它不会恢复纬度和经度。我需要帮助来控制 GPS，即“听”开和关事件，以便能够对其进行操作。谢谢！

this.geolocation.getCurrentPosition().then((resp) => {
this.global.latitude = resp.coords.latitude
this.global.longitude = resp.coords.longitude
  }).catch((error) => {
alert('Error getting location ' + error);
  });
  let watch = this.geolocation.watchPosition();
  watch.subscribe((data) => {
   this.global.latitude = data.coords.latitude
   this.global.longitude = data.coords.longitude
 });

Answer 1

手机的行为也会因您的准确度而异（例如：在 iOS 中，必须在 enableHighAccuracy 中“true”）。

我在定位功能方面也遇到了很多问题，最终解决了下一个问题：

创建 api.provider 并注入到组件中：

-geo 选项声明：

private geoOptions: GeolocationOptions = {
     enableHighAccuracy: true,
     timeout: 6000,
     maximumAge: 12000
};

-onInit 从构造函数调用：

public onInit(): Promise<any> {
        return new Promise<any>((resolve: (value?: boolean | any) => void, reject: (reason?: any) => void) => {
       this.getCurrentPosition().subscribe((response: any) => {
           resolve(response);
       }, (err: any) => {
           reject(err);
       });
   });
}

- 已经处理 getCurrentPosition 错误并改变精度选项以在执行 watchPosition 之前回调的构造函数：

constructor(public api: Api, private gps: Geolocation, private toast: ToastController) {
        const locationSubscription = this.isLocationActive.subscribe((response: any) => {
            const initExecute = () => {
                this.onInit()
                .then((val: any) => {
                    this.watchPosition().subscribe();
                    locationSubscription.unsubscribe();
                }).catch((reason: any) => {
                    // if fails, turn enableHighAccuracy options (some Android devices do not have HighAccuracy available)
                    this.geoOptions.enableHighAccuracy = !this.geoOptions.enableHighAccuracy;
                    initExecute();
                });
            };

            if (response && (response as boolean).toString().toLowerCase() === "true") {
                initExecute();
            }
        });
    }

- currentPosition 包装方法：

 public getCurrentPosition(): Observable<Geoposition> {
        // Create an Observable that will start listening to geolocation updates
        // when a consumer subscribes
        return Observable.create((observer: Observer<Geoposition>) => {
            this.gps.getCurrentPosition(this.geoOptions).then((response: any) => {            // your todo validator
                // this.validateGeolocationResponse(err, observer, true);
            }).catch((err: any) => {
                // your todo validator
                // this.validateGeolocationResponse(err, observer, true);
            });
            // When the consumer unsubscribes, clean up data ready for next subscription.
            // return { unsubscribe() { navigator.geolocation.clearWatch(watchId); }};
        });
    }

-最后是 watchPosition 方法：

public watchPosition(): Observable<Geoposition> {
        return Observable.create((observer: Observer<Geoposition>) => {
            this.gps.watchPosition(this.geoOptions).subscribe((response: any) => {
                // your validation method if coords are returned
                this.validateGeolocationResponse(response, observer);
            }, (err: any) => {
                // your validation method if coords are returned
                this.validateGeolocationResponse(err, observer, true);
            });
        });
    }

-提示 创建一个 ReplaySubject 来存储最后一个正确的坐标值。它并不总是成功返回，因此建议搜索最新的成功并在当前失败时将它们返回给您的订阅者。

例如：

public currentLocation = new ReplaySubject<Geoposition>(2);

也祝福你！