Cross Platform Apps

I am not much clear with the "Cross Platform Apps." Can we really built up some apps which can run on 开发者_开发百科iPhone/iPad , Android Phones/Tabs , Blackberry , Nokia (Any platform or more than one platform at least) ?

I have heard something like WAC , Titanium but really not clear with all these. Please help me out.

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There are some good frameworks out there to build cross-platform mobile applications:

1. Titanium: It is a framework to build Android, IPhone (and BlackBerry, still in beta it seems) using javascript, that will compile to native applications for the platforms specified.

2. Rhodes: A ruby framework, that supports almost all the mobile platforms out there (recently they added support to WP7). It has an MVC structure, and can use RhoSync to synchronize the data to a server side application.

3. PhoneGap: Another javascript framework, but it supports more platforms than Titanium, because it doesn't compile to native applications, but it embeds a web application inside a native application (web apps/web views are supported in each platform, so it's easier to handle the portability this way).

The apps will have access to the hardware, like the camera/gps, through some generic apis. In some case you can build specific native module to integrate them in just one application platform if you need to.

These frameworks are useful to build cross-platform application writing just one application, without having to write each single application with the platforms sdks. They have some (or many) limitations. If your application are simple enough you can consider using one of those framework. But for more complex ones, sometimes, if you target only a couple of plaforms, it could take less time to build each one with native sdks individually than using one of this cross-platform framework, because of their limitations (I highly prefer using the Android SDK than using Titanium).