ionic2 - Device Motion returning observable but unsubscribe gives error

Question

I am trying to detect motion using ionic2. Here is the snippet of my detectMotion.ts.

import {DeviceMotion} from 'ionic-native';
@Page({
    templateUrl: 'build/pages/pedometer/pedometer.html'
})
export class Pedometer {
   platform;
   watch;
   constructor () {
        this.platform = platform;
   }
   startWatching() {
       console.log('Starting to watch');
       this.watch = DeviceMotion.watchAcceleration(this.options);
       this.watch.subscribe(result => {this.detectMotion(result)});
   }
   stopWatching() {
       console.log('Stop Watching');
       // this.watch.dispose();
       this.watch.unsubscribe();
       // this.watch.clearWatch();
   }
   detectMotion(result) {
       console.log('Current Readings: '+ JSON.stringify(result) );
       //.....do something with the results.....
       this.stopWatching(); // Stop and wait for a second before restarting
       setTimeout(this.startWatching(), 1000);
   }
}

StartWatching is being called on a button click in the html. I have tried all 3 options that i could research on viz. unsubscribe; dispose; clearWatch But all in vain. The exact error that i have been getting is

error    ORIGINAL EXCEPTION: TypeError: Object #<Observable> has no method 'unsubscribe'

from the reference of ioni2 i learn that it returns a Observable

Any help or pointer is appreciated Thanks in advance

~Dhaval

Answer 1

As far as I know, you should store the subscription returned from the subscribe call, and call unsubscribe() to that.

You will get something like this:

export class Pedometer {
   platform;
   watch;
   watchSub : Subscription;
   constructor () {
        this.platform = platform;
   }
   startWatching() {
       console.log('Starting to watch');
       this.watch = DeviceMotion.watchAcceleration(this.options);
       this.watchSub = this.watch.subscribe(result => {this.detectMotion(result)});
   }
   stopWatching() {
       console.log('Stop Watching');
       // this.watch.dispose();
       this.watchSub.unsubscribe();
       // this.watch.clearWatch();
   }
   detectMotion(result) {
       console.log('Current Readings: '+ JSON.stringify(result) );
       //.....do something with the results.....
       this.stopWatching(); // Stop and wait for a second before restarting
       setTimeout(this.startWatching(), 1000);
   }
}