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[[Category:Symbian C++]][[Category:S60]][[Category:Porting to S60]][[Category:iPhone]]
==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. The APIs, tools and development environments are so dissimilar that it comes as quite a shock to many.

This article is meant to provide beginning and intermediate iPhone Os developers with an introduction to porting applications from iPhone to Symbian OS v9.x.

[[Image:Iphone.JPG‎]][[Image:Nokia-n97-2.jpg]]

The source porting should be rather easy, considering the similarities in functions provided by the languages, and the biggest differences in the code will appear in the GUI section.

iPhone OS development, as most of Mac development, is usually extensively based on MVC pattern. Thanks to this, most of the porting work should concern the graphical interface, while the model and controller part should remain close to basic translation, following the rules described bellow.

Of course, the more specific iPhone functions used, the more complex the port (GPS use, accelerator integration, SQLite data storage ...).

==Overview of iPhone OS and Symbian OS==

'''iPhone OS Architecture Overview'''
 
[[Image:IPhone Arc.jpg‎]]


'''Symbian OS Architecture Overview'''

[[Image:Symbian Arc.png‎]]

==Languages Used for Native Development==

iPhone OS: Objective-C

Symbian OS: Symbian C++

==Getting Started==

===IDEs===

* '''Symbian OS''': [http://www.forum.nokia.com/Resources_and_Information/Tools/IDEs/Carbide.c++/ Carbide.c++]
* '''iPhone OS''': [http://developer.apple.com/iphone/ XCode]


===Code: Similarities and differences===

Let's take a look at some code. The following table compares a code with the same logic written in Objective-C and Symbian/C++. The first thing to notice is that it is necessary to write some more lines of code in Symbian/C++ if compared to Objective-C. This is because some coding conventions that are used in Symbian/C++ and that characterize the way of programing. It is worth mention that Symbian/C++ is C++ with some coding convention that are related to memory management, naming of elements (classes, variables ...), etc. In the next lines the similarities among the languages will be highlighted. 

''NOTE: If you are not familiarized with C++ this can be a start point, but it is really recommended more information about the topic <<insert useful link here>>. The comparisons will be among Objective-C with C++ and Symbian/C++ (that involves the coding conventions)'' 

====Similarities====

* The basic similarity is that both languages Objective-C and C++ came from the necessity to increment the C language with support to object oriented skills. 
* Other aspect is that both languages uses the same extensions for the files designed to have the classes declarations: '''.h'''. Regarding the source file, Objective-C uses the extension '''.mm''' and C++ uses the extension '''.cpp'''
* In both languages there is a clear separation between classes declarations and implementations. The separation is clear on the code where it can be seen '@interface' keyword of Objective-C matching the 'class' keyword of C++. In fact, except the code added for object construction of Symbian/C++ every line of code of the Brad Cox's language (creator of Objective-C) has a very similar line of code in C++.
* The scope delimiter of the instance variables are also the same, i.e., @private, @protected and @public delimiters are available in C++. 
* Other similarity is that in Symbian/C++ there is also a common base class 'CBase', similar to 'NSObject', that is used in all classes of type 'C'. In Symbian/C++ every class has a type. The 'C' classes are dynamic allocated on heap and have a special construction mechanism called [[Two-phase_construction]]. Besides this type are others like 'T' classes that are usually used for stack based objects. More information regarding the types of classes of Symbian/C++ can be found here 
**[[C_class]]
**[[R_class]]
**[[M_class]]
**[[T_class]]

====Differences====
* There is no standard way to synthesize methods in C++. So every @property on Obj-C code has to be implemented. In this case the property myProperty has the equivalent methods '''TInt myProperty()''' and '''void setMyProperty(TInt property)'''.

* Static methods are declared with a '''static''' keyword in C++ instead of '''+''' sign in Cbj-C. Regarding the variables the same keyword is used in both cases.

* You need to write special code for object construction in classes of type ''C''. This special code is called [http://wiki.forum.nokia.com/index.php/Two-phase_construction two phase construnction]. The first construction step consist of calling the C++ constructor that shouldn't alloc any resource. In the second phase, you call the method ConstructL that effectively alloc the resources for the object. Also, in the wo phase construction you should be aware of the cleanup stack mechanism that Symbian adopts and use it accordingly (see [http://wiki.forum.nokia.com/index.php/Cleanup_stack Cleanupstack]).


{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]]
! style="width:50%;"| [[Image:S60_small.jpeg]]
|- valign="top"
| 
<code language="objc">

#import <NSObject.h>

@class Bar;
@interface Foo : NSObject
{
@private
    double x;
    Bar* mybar;
    int myProperty;
}

@property int myProperty;

-(void) useBar;
     
-(int) doSomething:(int)arg;
     
-(int) doOtherThing:(int)arg1 :(int)arg2;

+(double) doThingsForThisClass:(double)arg;

@end
     
@implementation Foo


@synthesize myProperty;

-(void) useBar
{

}
     
-(int) doSomething:(int)arg 
{
      return arg;
}
   
-(int) doOtherThing:(int)arg1 :(int)arg2 
{
      return arg1+arg2;
}

+(double) doThingsForThisClass:(double)arg
{
      return arg;
}
@end
</code>
| 
<code language="cpp"> 
#ifndef __FOO_H__
#define __FOO_H__

#include <e32def.h>

class CBar;

class CFoo : public CBase
{
private:
      TReal iX;
      CBar* iMyBar;      
      TInt iMyProperty;
      
      /* Code added for object construction 
      in Symbian/C++*/
      CFoo(){};
      void ConstructL(){};
public:
      /* Code added for object construction 
      in Symbian/C++*/
      static CFoo * NewL(); 

      TInt myProperty();
      void setMyProperty(TInt property);
      
      void useBar();
     
      TInt doSomething(TInt arg);
     
      TInt doOtherThing(TInt arg1, TInt arg2);
 
      static TReal doThingsForThisClass(
                                   TReal arg);
};

/* Code added for object construction 
in Symbian/C++*/

CFoo* CFoo::NewL()
{
       CFoo* instance = new (ELeave) CFoo;
       . . .
       instance->ConstructL();
       . . . 
       return instance;
}

TInt Foo::myProperty()
{
     return myProperty;
}

void Foo::setMyProperty(TInt property)
{
     iMyProperty = property;
}
 
void Foo::useBar()
{
}
     
TInt Foo::doSomething(TInt arg) 
{
      return arg;
}
   
TInt Foo::doOtherThing(TInt arg1,TInt arg2) 
{
      return arg1+arg2;
}
 
TReal Foo::doThingsForThisClass(TReal arg)
{
      return arg;
}

#endif  
</code>
|}

===Key Points to Remember===
*Use #include instead of #import in Symbian C++
*Use NULL instead of nil in Symbian C++
*It is really a good practice to separate the UI and Engine part of the code separately following the MVC [[Design_Patterns_in_Symbian ]].


====Methods====
{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]] Objective-C Messages
! style="width:50%;"| [[Image:S60_small.jpeg]]
|- valign="top"
| 
Objective-C Example:

<code language="objc">


   /* Objective-C is a language with
      “function calls using brackets”.
      [object doSomething]; ;*/

   [receiver message];
</code>

To get an object to do something, programmer has to send it a message telling it to apply a method.

Note: The receiver is an object, and the message tells it what to do.
|

Symbian C++ Example:

<code language="cpp">

   /* Symbian C++ is a language with
      “function calls using parentheses”.
      object.doSomething();*/

   Receiver* receiver = new(ELeave) Receiver();
   receiver->Message();

   // deletion of the allocated object 
   delete receiver;
   receiver = NULL;

</code>
|}

====Methods With Arguments====
{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]]
! style="width:50%;"| [[Image:S60_small.jpeg]]
|- valign="top"
| 
Syntax:
<code language="objc">
[receiver meassage:Argument1];
</code>

Obective-C Example:
<code language="objc">
// example 1
[myRectangle setWidth:20.0];

// example 2
[myRectangle setOriginX: 30.0 Y: 50.0];
</code>
|
Symbian C++ Example:
<code language="cpp">
TRect rect(0,0,0,0);

rect.SetRect(10,20,30,40);
</code>
|}

====Nested Messages====
{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]]
! style="width:50%;"| [[Image:S60_small.jpeg]]
|- valign="top"
| 
Objective-C Example:
<code language="objc">
[myRectangle setPrimaryColor:[otherRect primaryColor]];
</code>

One message expression can be nested inside another.
|
Symbian C++ Example:
<code language="cpp">
TRect rectA(10,20,30,40);
rectA.SetSize(TSize(30,40));
</code>
|}

====Allocation Of Object====
{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]]
! style="width:50%;"| [[Image:S60_small.jpeg]]
|- valign="top"
| 
Objective-C Example:
<code language="objc">
Object *object = [[Object alloc] init];
</code>

There is also an autorelease pool that can be used to avoid manual desallocation, but it must be used with caution, since desallocation occurs at the end of the context (useally as the method returns), while you may need to desallocate it sooner for many reasons.
|
Symbian C++ Example:
<code language="cpp">
Object *object = new(Eleave) Object();
</code>
|}

====Deallocation Of Object====
{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]]
! style="width:50%;"| [[Image:S60_small.jpeg]]
|- valign="top"
| 
Objective-C Example:
<code language="objc">
// deallocation of objects
[object release] ;
[super dealloc];
</code>

In second line we are sending a message to a superclass NSObject in most of the case to do its cleanup. If we dont do this the object will not remove and it is a memory leak.
|
Symbian C++ Example:

<code language="cpp">
delete object;
object = NULL;
</code>
|}

==Porting Application to Symbian==
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
<br><br>
List of files look like in Xcode
<br>
[[Image:IphonesFiles.jpg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]] 
* [[How_to_create_project_in_Carbide.c%2B%2B_for_the_s60]]
* [[Directory_layout_of_Symbian_projects]]  
    </td>
  </tr>
</table>             

<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
Interface Builder iPhone:

Every project gets one nib file by called which is called "MainWindow.xib" which can be found under "Resources". An iPhone application has only one window (MainWindow.xib).Double click on "MainWindow.xib" to launch the Interface Builder, which will open four windows and one of the window will look like this.

Every nib file has atleast two files.File's Owner and First Responder which cannot be deleted. Every other objects apart from the first two, represents an instance of an object which gets created when the nib file loads. 

* File's Owner simply shows that it owns the object in the nib file. 

* First Responder tells us which object are we currently interacting with; like the textbox, buttons... 

* The third object which is special to the MainWindow.xib file is called "Hello Universe App Delegate" and this file represents "HelloUniverseAppDelegate" class. Last but not the least the view represents the object which we design in our apps.


[[Image:InterfaceBuilder.jpg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[RSG_File]] 
    </td>
  </tr>
</table>



===Main Function===
{| style="width:100%;" cellpadding="10"
|- align="left"
! style="width:50%;"| [[Image:Apple.jpeg]]
! style="width:50%;"| [[Image:S60_small.jpeg]]
|-valign="top"
| 
<code cpp>
#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;
}
</code>
|
<code cpp>
#include <eikstart.h>
#include "CUSSDApplication.h"

LOCAL_C CApaApplication* NewApplication()
{
	return new CMyApplication;
}
/* Entry Point for Symbian GUI */

GLDEF_C TInt E32Main()
{
	return EikStart::RunApplication( 
                            NewApplication );
}
</code>

* [[GUI_vs._Console]]
* [[Polymorphic_DLL]]
* [[Static_dll]]
|}

===Porting GUI Application to Symbian ===

====GUI Overview====
<br><br>
[[Image:Iphone ui.jpg‎]][[Image:Symbian ui.jpg‎]]

[[Image:S60_small.jpeg]]
*[[GUI_Framework]]

====Orientation In UI Application====
<table width="100%" order="1" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]

The [http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIApplication_Class/Reference/Reference.html#//apple_ref/c/tdef/UIInterfaceOrientation UIInterfaceOrientation] key provides a hint to iPhone OS.
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[Change_screen_orientation_of_UI_application]]
    </td>
  </tr>
</table>

===Graphics And Drawing===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
* iPhone OS supports drawing through the OpenGL ES (OpenGL ES v1.1),Quartz,UIKit, or Core Animationframework. The [http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIView_Class/UIView/UIView.html UIView] class makes the update process easier and more efficient.
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
* S60 has the support of OpenGL ES.
    </td>
  </tr>
</table>


'''Supported Images'''

{| class="wikitable sortable" border="1" style="width: auto;"
|-
! width="150" | Format
! width="150" | Extension
! width="150" | iPhone
! width="150" | S60
|-
|Portable Network Graphic(PNG)
|.png
|yes
|yes
|-
|Tagged Image File Format(TIFF) 
|.tiff, .tif
|yes
|
|-
|Joint Photographic Experts Group(JPEG) 
|.jpeg, .jpg
|yes
|yes
|-
|Graphic Interchange Format(GIF) 
|.gif
|yes
|yes
|-
|Windows Bitmap Format (DIB) 
|.bmp, .BMPf
|yes
|yes
|-
|Windows Icon Format 
|.ico
|yes
|
|-
|Windows Cursor 
|.cur
|yes
|
|-
|XWindow bitmap 
|.xbm
|yes
|
|-
|MBM
|.mbm
|no
|yes
|}



'''Simple Graphics API'''

{| class="wikitable sortable" border="1" style="width: auto;"
|-
! width="150" | iPhone
! width="150" | Use
! width="150" | S60
|-
|UIImage
|class for displaying images
|CFbsBitmap,CGulIcon
|-
|UIColor
|provides basic support for device colors
|TRgb
|-
|UIFont
|font information
|CFont
|-
|UIScreen
|provides basic information about the screen
|CWsScreenDevice
|}

===Event Handling===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
* Does Not Support the Key Events.
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
* Does not support the multi-touch till now.
*[[Using_basic_touch_gestures]]
*[[A_tour_to_the_S60_Touch_UI_components]] 
    </td>
  </tr>
</table>

===DataBase Handling===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[DBMS]]
    </td>
  </tr>
</table>

===Communication Handling===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]

Apple provides built-in support for the http, mailto, tel, and sms URL schemes. It also supports http–based
URLs targeted at the Maps, YouTube, and iPod applications. Applications can register their own custom URL
schemes as well. To communicate with an application, create an ''NSURL'' object with some properly formatted
content and pass it to the openURL: method of the shared ''UIApplication'' object.
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[Symbian_C%2B%2B_Messaging_Articles]]
*[[Symbian_C%2B%2B_Networking_Articles]]
*[[Symbian_C%2B%2B_Connectivity_Articles]]
*[[Symbian_C%2B%2B_Telephony_Articles]]

<br><br>
'''InterProcess Communication'''
*[[Message_Queues]]
*[[Inter_Process_Communication_in_Symbian]]
    </td>
  </tr>
</table>

===Sensor Handling===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[Nokia_Sensor_APIs]]
*[[S60_Sensor_Framework]]
    </td>
  </tr>
</table>

===MultiMedia Framework===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[Symbian_C%2B%2B_Multimedia_Articles]]
    </td>
  </tr>
</table>

===XML Handling===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[How_to_parse_XML_file_using_CParser_class]]
    </td>
  </tr>
</table>

===Security Framework===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[Symbian_C%2B%2B_Security_Articles]]
    </td>
  </tr>
</table>

===Application Signing Overview===
<table width="100%" cellpadding="10">
<tr>
    <td width="50%" valign="top">
[[Image:Apple.jpeg]]
    </td>
    <td width="50%" valign="top">
[[Image:S60_small.jpeg]]
*[[Symbian_C%2B%2B_Application_Signing_Articles]]
    </td>
  </tr>
</table>

===Application Bundle ===

{| class="wikitable sortable" border="1" style="width: auto;"
|-
! width="150" | Objective-C
! width="150" | Symbian C++
! width="150" | Remarks
|-
|MyApp.app
|MyApp.exe
|The executable file containing your application’s code.
|-
|Icon.png
|Icon.mbm
|Represent your application on the device home screen.
|-
|MainWindow.nib
|MainWindow.rss
|Typically, this nib file contains the application’s main window object.This could be compared to Symbian Resource file but to a full extent.
|-
|Info.plist
|Symbian Package file.
|information property list, this file is a property list defining key values for the application, such as bundle ID, version number, and display name
|-
|
en.lproj 
fr.lproj 
es.lproj
|
en.l01 
fr.l01 
es.l01
|Localized resources.
|-
|MyApp.app
|MyApp.SISX
|Final ouput file .
|}

==Technical References==

===External===
*[http://developer.apple.com/ Apple]
*[http://developer.symbian.org/wiki/index.php/Writing_portable_code_and_maintaining_ports Writing portable code and maintaining ports]

===Internal===
====Introductory References====
*[[How_do_I_start_programming_for_Symbian_OS%3F]]
*[[SIS]]
*[[How_to_define_application_icon]]
*[[Design_Patterns_in_Symbian]]
*[[MMP_file]]
*[[UID]]

====Signing And Security References====
*[[Application_Signing]]
*[[Advanced_Package_File_Options]]

====Binary Compatibility====

====Tools====
*[[Symbian_C%2B%2B_Tools_Articles Tools Articles]]

===Books===
*[[Symbian_Resources_and_Books]]
*[http://library.forum.nokia.com/ Library.forum.nokia]

===WebSites===
*[http://www.forum.nokia.com Forum Nokia]