Is there a strategy or at least best practice to write an app that runs on iPhone, BlackBerry and Android?
I'm ignorant about the development environments for BB and Android, but I assume they both support Java apps.
I know that the iPhone would require an ObjectiveC portion (as well as a whole new UI).
Has anyone done this?
When writing multiplatform apps, you need to decide how much of the code to share. The 2 options are
The 2nd approach tends to give better apps but it is a more work (assuming you don't need to write the cross platform libraries).
The tricky thing with the mobile world is picking a language. Right now you have
You can cross compile java to javascript and vice versa. You can also compile java to C or use a javascript engine that you can call from C. I don't think you can run C on a java/javascript phone. That leads me to suggest writing your code in Java/Javascript. Cross compiles (and mixing languages in general) have the downside of making debugging a bit harder.
http://j2mepolish.org could be good choice, however, iphone is only in the roadmap. But android and BB are already supported as well as all other j2me phones.
Another option to look at is Rhodes, which is a Ruby framework.
also if you're writing games, check out my cross-platform (iPhone, Android, etc.) solution called the Cuttlefish Engine, at http://www.cuttlefishengine.com.
One technique, that works suitably for certain kinds of apps such as reference applications: Use HTML/CSS/JavaScript and write compact clients that uses the platform's HTML viewer object to read locally embedded web content.
One technique to write cross-platform application that ran on both BlackBerry and Windows Mobile, was to write it all in HTML. I had to use a subset of HTML and CSS that worked on both BlackBerry Browser and Pocket Internet Explorer. I used a small amount of JavaScript as well.
I wrote very small viewers that ran it off internally-stored HTML and images using jar:// (BlackBerry) and res:// (Windows Mobile) URL's. I was able to embed all the HTML and images files as part of the BlackBerry application, by using a custom version of the browser field and . Same for Windows Mobile, I was able to use Pocket Internet Explorer as an embedded ActiveX in my Windows Mobile application.
Note -- for BlackBerry, I had to support legacy devices running OS 4.2. To do so, I recycled a lot of RIM code samples, such as SecondaryResourceFetchThread.java to pull images embedded in the application, and deliver it to through a custom connection object that implemented HttpConnection that I designed to handle jar:// URL's for internally embedded HTML/images in my BlackBerry application. It was a little tricky to figure out. For Windows Mobile, it was more intuitive.
There are other ways to do what I needed, but it worked perfectly for a medical reference application, and I was able to design separate CSS files for BlackBerry and for Windows Mobile to reformat the content slightly differently for the two mobile devices. (It was kind of like testing Netscape versus Internet Explorer compatibility in the old days.)
This may not work for your situation, but if your application is a web-style 'reference' application, and you know how to do HTML well, this approach may work.
Another interseting option is mobile processing, @ http://mobile.processing.org Based on a java platform
We are currently looking into this also and we found:
Titanium: http://www.appcelerator.com/products/titanium-mobile-application-development/
Kony Solutions: www.konysolutions.com/wore.php
These products have good reviews. The Titanium is free for the community edition.
Also, you could give a try to Mobile Community Framework (MCF). This is a crossplatform framework running natively on iPhone, Android, WinMobile, Symbian and BlackBerry. MCF handles network, location and proximity operations for you, in a Wi-Fi Ad-Hoc network or through dedicated proxy server if no direct connection is possible. It has simple API, and it's free to use. This way you can develop your app interface and logic separately on each platform, and use MCF to connect instances of your application in a way you like.
More info at http://uvamobiltec.com
You can always write a javascript app on the web, and it should work on all three. Of course that doesn't get installed on the phone.
Android has a webview that runs Javascript. I'm sure the other platforms do also. If you wrote most of your logic in javascript, you could may be able to reuse that javascript across platforms.
Yet another framework is http://www.mosync.com/
It seems to support all major platforms.