Archived:Porting iPhone native (Objective-C) applications to Qt for Symbian

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Created: jaaura (07 Apr 2009)

Last edited: hamishwillee (11 Oct 2012)

Introduction

When someone familiar with developing for iPhone (Mac Os) Os moves to developing for Symbian OS, there is a period of uncertainty about where to start. Objective-c is used for the native application development in iPhone while in Symbian OS Symbian c++ is used for this purpose. Qt is now becoming a popular among the mobile

developer because of its easy syntax and cross platform capability. Application development using Qt is capable of running on various platform like Windows, Mac-OS, Linux, Symbian. While objective-c application can not provide such a liberty.

This article is meant to provide beginning and intermediate objective-c developers with an introduction to porting applications from objective-c to Qt.

Overview of Objective-c and Qt architecture

iPhone objective-c application based on the architecture given below.

Qt Architecture Overview

Languages Used for Native Development

iPhone OS: Objective-C

Symbian OS: Symbian C++,Qt

Tools

	Qt	Objective-C
IDE	Carbide C++,Qt creator	XCode

Organization Of Source Code

Extension	Objective-c	Extension	Qt
.h	Header file	.h	Header file
.m	Source file	.cpp/.c	Source file
.mm	Source files(if actually refer to C++ classes or features from your Objective-C code)	.cpp	Source file

main() function comparison

Objective-C main() function

#import <UIKit/UIKit.h>
int main(int argc, char *argv[])
{
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, nil, nil);
[pool release];
return retVal;
}

Here actual user code is written in the UIApplicationMain function which is called as soon as application loading is completed.

Qt main() function

#include <QApplication>
 
#include "digitalclock.h"
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    DigitalClock clock;
    clock.showMaximized();
    return app.exec();
}

Here user code is written in a separate .cpp file or can be written in the main file also.

Main difference : Qt uses a #include while objective-c uses a #import.