Ionic 2 cordova-plugin-mauron85-background-geolocation不更新UI

Question

我是Ionic和Typescript的新手,如果我对这张脸有屁股,那么道歉!

我试图用Ionic 2构建一个简单的iOS和Android应用程序,只显示用户当前位置,在移动时进行更新.

我面临的问题是,虽然我似乎正在通过UI获取坐标位置,但永远不会更新以显示更新的位置.

我使用cordova-plugin-mauron85-background-geolocation插件创建了一个提供程序作为location.ts:

import { Injectable, NgZone} from '@angular/core';
import { BackgroundGeolocation } from 'ionic-native';

@Injectable()
export class LocationProvider {

public message: any = "I'm new here";
public latitude:number = 0.0;
public longitude:number = 0.0;
private zone: NgZone;

constructor() {
   this.initialiseLocationManager();
}

initialiseLocationManager() {

let config = {
        desiredAccuracy: 1,
        stationaryRadius: 1,
        distanceFilter: 1,
        interval:1000,
        activityType:'AutomotiveNavigation',
        debug: true,
        stopOnTerminate: true,
};

BackgroundGeolocation.configure(config)
     .then(this.locationUpdated)
     .catch((error) => {
          console.log('BackgroundGeolocation error');
      });
}

private locationUpdated(location) {
   console.log('******* NEW LOCATION ********');
   this.zone.run(() => {
     this.latitude = location.latitude;
     this.longitude = location.longitude;
 });

 BackgroundGeolocation.finish(); // FOR IOS ONLY
}

private error(error) {
   console.log('ERROR');
}

public startTracking() {
  BackgroundGeolocation.start();
}

public stopTracking() {
   BackgroundGeolocation.stop();
}
}

然后我将其注入我的页面test.ts:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
import {LocationProvider} from '../../providers/location/location';

@Component({
  templateUrl: 'build/pages/test/test.html', 
})
export class TestPage {

  constructor(private nav: NavController, private     locationProvider:LocationProvider) {

  }

  startTracking() {
    this.locationProvider.startTracking();
  }

  stopTracking() {
    this.locationProvider.stopTracking();
  }
}

我的页面内容是:

<ion-header>

  <ion-navbar>
    <button menuToggle>
      <ion-icon name="menu"></ion-icon>
    </button>
    <ion-title>Test</ion-title>
  </ion-navbar>
</ion-header>


<ion-content padding>
  <button (click)="startTracking()">
    Start Tracking
  </button>
  <button (click)="stopTracking()">
    Stop Tracking
  </button>

  <ion-item>Latitude / Longitude</ion-item>
    <ion-item>
      {{locationProvider.latitude}},{{locationProvider.longitude}}
    </ion-item>
</ion-content>

当我为iOS编译我的应用程序并在Xcode中运行它看起来像我期望的那样,当我点击"开始跟踪"按钮时,我看到Xcode控制台中的条目表明正确地获得了位置,即

2016-08-06 12:37:17:370 Test[3264:62403] Better location found: Location: id=0 time=140310177131584 lat=51.8724580445 lon=-2.26443678245263 accu=5 aaccu=-1 speed=-1 head=-1 alt=0 type=current
2016-08-06 12:37:17:371 Test[3264:62403] LocationManager queue Location: id=0 time=140310177131584 lat=51.8724580445 lon=-2.26443678245263 accu=5 aaccu=-1 speed=-1 head=-1 alt=0 type=current
2016-08-06 12:37:18:370 Test[3264:62403] LocationManager didUpdateLocations (operationMode: 1)
2016-08-06 12:37:18:370 Test[3264:62403] Location age 0.001122
2016-08-06 12:37:18:370 Test[3264:62403] Better location found: Location: id=0 time=140310177372752 lat=51.8726980292 lon=-2.26504136905789 accu=5 aaccu=-1 speed=-1 head=-1 alt=0 type=current
2016-08-06 12:37:18:370 Test[3264:62403] LocationManager queue Location: id=0 time=140310177372752 lat=51.8726980292 lon=-2.26504136905789 accu=5 aaccu=-1 speed=-1 head=-1 alt=0 type=current

但是页面上显示的坐标似乎永远不会刷新并更新真实位置.

我可能错过了明显的,但看不到它,所以任何建议都会非常感激.

Answer 1

您现在可能已经解决了这个问题，但问题出在这一行：

BackgroundGeolocation.configure(config)
 .then(this.locationUpdated) <-----
 .catch((error) => {
      console.log('BackgroundGeolocation error');
  });
}

所以你的回调将被触发，但它会丢失this的上下文。

您需要使用.bind()发送正确的上下文

BackgroundGeolocation.configure(config)
 .then(this.locationUpdated.bind(this)) <-----
 .catch((error) => {
      console.log('BackgroundGeolocation error');
  });
}