Wednesday, 27 February 2013

Launch a website as a mobile app using PhoneGap/Apache Cordova


How to launch a website as a mobile app using PhoneGap/Apache Cordova


I spent some time recently trying to find out how to launch my website as a mobile app.  The information was available around the internet but since it took me a while, I thought I'd collate it here in one simple post for anyone who wants to do the same

I decided to use Apache Cordova since it gave me the framework for developing an HTML5 site as a mobile app already, meaning all I really needed to do was plug my website into it.  Their getting started guide has good information on how to create a Cordova project - I used Android but you can use whatever means you wish

A basic Cordova app gives you a way to launch the app with an HTML page that you use to display your app contents.  The trick then is make the page load your website which you can do in one of 3 ways:

1. Package your site inside the app. This means it loads fast and without an internet connection.  The downside is you have to update and re-release the app whenever your website changes. It also needs to use relative paths since the root directory will be the mobile device's root directly, not the root of your site
2. Point the page at your remote website, which means changes are picked up immediately.  The downside is that it won't work if the phone has no internet connection
3. Do both and fall back to the local site if there is no network connection

Option 1 - Package your website inside the app

If you want to do option 1 (package your site with the app) you simply copy your entire site into the assets > www directory which will load your homepage as a local page (I think PhoneGap Build insists this is index.html, but if you're loading from code you just launch Cordova with that page name). Simple. You need not read on unless you're interested in option 2 or 3

Option 2 - launch your external website inside the app

To load a remote site, you need to load your homepage (or any page) using javascript from the html page that Cordova will open in your app.  This is relatively simple using basic javascript
window.location="http://your.website";

The recommended way to run javascript in a Cordova environment is to use Cordova's ondeviceready event which ensures it is loaded, which can be hooked into your page

document.addEventListener("deviceready", onDeviceReady, false); 
function onDeviceReady() {
    // Now safe to use the Codova API
window.location="http://your.website"; }

This is probably not strictly necessary for this javascript call, which is not using the Cordova API.  However I am using because it is needed for option 3

You also need to tell Cordova that it is safe to load your website in the cordova.xml properties (you can remove the subdomains part if you don't have any)
<access origin="http://your.website" subdomains="true"/>

At this point you are good to go!

Option 3 - launch your external website but fail back to local version

This option requires a little more work but gives you the advantage of displaying a set of files packaged with the app if there is no internet connection

Since you need the html page given by Cordova in assets > www you will need to copy your local site to a subdirectory (I've called it local), and do everything in option 2 to load the remote site

All you need then is to add some logic to decide whether there is an internet connection and act accordingly.  Fortunately Cordova gives us a solution to this

Firstly, add a javascript function to check the connection type

   function checkConnection() {
         var networkState = navigator.network.connection.type;
         var states = {};
         states[Connection.UNKNOWN]  = 'Unknown connection';
         states[Connection.ETHERNET] = 'Ethernet connection';
         states[Connection.WIFI]     = 'WiFi connection';
         states[Connection.CELL_2G]  = 'Cell 2G connection';
         states[Connection.CELL_3G]  = 'Cell 3G connection';
         states[Connection.CELL_4G]  = 'Cell 4G connection';
         states[Connection.NONE]     = 'No network connection';
       
         return networkState;
       
     }

Then add some logic around the window.location call to load the appropriate site

   function onDeviceReady() {
   var networkState = checkConnection();
 /* load local files if there is not network connection */
                  if (networkState == Connection.NONE) {
                      window.location="local/index.html";
                  } else {
              window.location="http://your.website";
                  }
   }

Again, you're good to go!

As an alternative to option 2 or 3 (I'll call it option 2a) you could use the connection type logic to display an error message so you don't attempt to load the external site when there is no connection eg:

   function onDeviceReady() {
   var networkState = checkConnection();
 /* load local files if there is not network connection */
                  if (networkState == Connection.NONE) {
                  navigator.notification.alert('This app requires an internet connection');
                  } else {
               window.location="http://your.website";
                  }
   }
I'm going to wrap a framework around this and release some instructions for non-developers to produce site launchers for mobile devices using PhoneGap build.  Watch this space

23 comments:

  1. This was a good suggestion that you put up here...dude…..hope that it benefits all the ones who land up here. 

    Edmonton Mobile App Development

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  2. This comment has been removed by a blog administrator.

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  3. Trying to do step 2 here, but unsuccessful. Wondering if you could help me out really quick. I would greatly appreciate it.

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  4. Got it to work, minus the site styling. Shouldn't it be pulling in all the styling as well (using step 2)?

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  5. Hi, yes it should, it's just CSS so the styles should get pulled in from there. Are they hosted externally to your normal site, or in a subdomain? Could be the access origin

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  6. Hi,

    Thanks for the great tips. Exactly what i needed when i needed it!

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  7. Option 2 open browser and loads website. where did i go wrong?

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  8. Hi

    I'd probably need a bit more information than that but it could be that you didn't set the access origin, are pointing your launch file to the remote page instead of the local one, haven't set cordova up properly ... if you can provide your cordova.xml, local html code etc I might be able to help but otherwise that question is too vague

    Antony

    Antony

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  9. I have php scripts running back end of my mobile website ,is it possible to deploy my website as an app with option 2
    thanks in advance

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  10. Hi, no, cordova doesn't run PHP which is a server-side language I'm afraid
    Antony

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  11. These tips are always work for me.. thanks for sharing these info.. i will always take care of these...

    make mobile website

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  12. Hi Antony. Great job!. I have a question, cordova.js (at least now) is a different file in iOS than in Android. How do you handle this script inclusion on the 'remote' website?

    Thanks a lot

    Edgar

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  13. Hi, I think that depends on what you are trying to do? The remote site doesn't need cordova.js is all you are doing is redirecting to it, only the launch page needs it which is local anyway

    Antony

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  14. Thanks for sharing this code, very useful.

    Just want to share a couple of fixes I had to make to get it working with PhoneGap 3. I had to change:

    var networkState = navigator.network.connection.type;

    to

    var networkState = navigator.connection.type;

    And make sure the appropriate plugin was installed on the command prompt:

    phonegap local plugin add https://git-wip-us.apache.org/repos/asf/cordova-plugin-network-information.git

    Worked after that!

    Again, thanks for sharing .. was a big help.

    - Mark

    Freelance Software Developer

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  15. very nice blog.
    but i have one issue.
    function onDeviceReady()
    {
    document.addEventListener("backbutton", onBackKey, false);
    window.location="../index.jsp";
    }
    once i switch to the index.jsp .i looses the functionality of phonegap
    example :- backbutton event not execute

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  16. I was wondering if it is possible to access the PhoneGap/Cordova API from within the mobile app. Basically, I would like to choose option 2. If the mobile site (written in Backbone + Marionette) detects that it is called from the PhoneGap wrapper, it exposes some additional functionality (such as GPS tracking).

    So far I managed to implement the basics of option 2. However, while a call to a arbitrary PhoneGap API method (navigator.connection.type) seems to work from PhoneGap's index.html, I can't manage to call it from my mobile app, even though I included cordova.js. It just doesn't seem to trigger the deviceready event, and navigator.connection is undefined.

    Perhaps related, I'm also getting the error "Uncaught SecurityError: Blocked a frame with origin "http://mysite.com" from accessing a frame with origin "http://localhost:8000". Protocols, domains, and ports must match."

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  17. This comment has been removed by the author.

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  18. thanks for sharing antony!

    @ruben stranders, trying to implement exactly your described problem at the moment...
    can you be more specific on "... I included cordova.js." is cordova.js on the remote mobile website or in the local cordova app? if second (which would be the better solution as far as i can see, to support different corona.js versions for ios/android) could you please describe how to manage to include the cordova.js to your remote mobile website? thanks a lot.

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  19. @Ruben, that's exactly the thing I would be interested to know. As far as I have heard, it's not possible but maybe just because ppl didn't try hard enough?

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  20. If anybody come across with file to found: www/"http://google.com" error, advice to use window.open("http://google.com"); instead of window.location

    Fahid Mohammad - aka (Volcano)

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