Qt is a cross-platform application framework. Using Qt, you can write applications once and deploy them across many desktop and embedded operating systems without rewriting the source code.
Qt's vision is to have Qt Everywhere and to enable you to create advanced applications with innovative user experiences while getting to market quickly. Qt allows you to code once and deploy across major device and desktop operating systems.
Qt development is done in standard C++ rather than the Symbian C++ dialect used by Symbian. The Qt APIs provide a higher level of abstraction than the Symbian APIs. This means development is easier and you will get results much quicker.
If you have only developed with Symbian C++ then you will need to learn a few new ways of doing things. However, your general programming skills will transfer easily and the discipline you have learned from Symbian C++ will be well rewarded. Some information about transferring Symbian C++ concepts can be found in the Symbian paradigms section.
Developing Qt applications for Symbian follows much the same process as developing for Symbian, i.e. you can use the same development environment (Symbian C++ SDKs, Symbian emulator and Carbide.c++); you can use the same build and debug features inside Carbide.c++; and applications are packaged in .sis files for installation on the phone.
Support for Qt development has been integrated into Carbide.c++ which simplifies the development of Qt applications. The Qt APIs are very well documented and are available here.
Note: The only supported development environment for Qt for Symbian is Carbide.c++ (version 2.0.2)
Qt has its own GUI widget set so you will not be using the Symbian UI widgets. However, the Qt UI widgets look and behave like their Symbian counterparts.