myProperty

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  myService: Ember.inject.service('my-service')
});

services.my-service.js

import Ember from 'ember';

export default Ember.Service.extend({
    myProperty: false,

    toggleMyProperty() {
      this.toggleProperty('myProperty');
      console.log('toggleMyProperty');
    }
});

templates.application.hbs

{{#if myService.myProperty}}
	<h1>myProperty is set</h1>
{{else}}
	<h1>myProperty is NOT set</h1>
{{/if}}

<button onclick={{action myService.toggleMyProperty}}>Toggle!</button>

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.0",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.0",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}