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<concept id="GUID-07D2ED79-90B2-4ABC-A61F-108DAEE21955" xml:lang="en"><title>Implementing
framework requirements</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<fig id="GUID-0BBC3D60-0EF0-4446-A1A5-CF84A4728C72"><title>Application Menu</title><image href="GUID-3382507E-1B21-418C-A908-DD3F688C0672_d0e36776_href.png"/></fig>
<p>In the Symbian platform, mobile device users start applications from
the application menu. When the mobile device user selects an application,
the application framework calls the application's entry point to launch the
application. In some cases, applications can also be started by other executables.</p>
<fig id="GUID-5A76CBEA-8AF3-4F68-B2FB-9F402D748DF3"><title>Application launch</title><image href="GUID-CC4CA423-0A14-457C-8CBE-4A9F0E8D0B96_d0e36784_href.png"/></fig>
<p>When an application starts, objects are created in the following order:</p>
<ol>
<li id="GUID-BC07E865-8B42-4654-90F9-4644B202EDBC"><p>application
(<xref href="GUID-4F825D83-47A4-36C9-9A25-943A6D799F84.dita"><apiname>CAknApplication</apiname></xref>)</p></li>
<li id="GUID-0B6D8737-8FC7-486B-B3ED-6F91CFA69670"><p>document (<xref href="GUID-935C59EE-AD66-33FE-987B-BD97F5147CC1.dita"><apiname>CAknDocument</apiname></xref>)</p>
</li>
<li id="GUID-FAAD10CF-2F0F-4589-B2B8-A2A8A3696CA5"><p>UI controller
(<xref href="GUID-6F2BAB12-6273-3314-B9F1-9AA08403F5EF.dita"><apiname>CAknAppUI</apiname></xref> or <xref href="GUID-9CB85702-5D4F-371E-99D0-F6030DC86539.dita"><apiname>CAknAppViewUI</apiname></xref> depending
upon your approach)</p></li>
<li id="GUID-ED56D892-18C4-447C-A7AB-811E1D90C2DA"><p>view controller
(<xref href="GUID-11967EBB-7439-3775-B287-7560ECA0AF1F.dita"><apiname>CAknView</apiname></xref>) in <xref href="GUID-68B999C2-0993-4804-9624-42C3D88BE5C7.dita">Symbian
view applications</xref></p></li>
<li id="GUID-5BFF07E4-6575-4B23-9FA5-824DB057A55C"><p>view (<xref href="GUID-B06F99BD-F032-3B87-AB26-5DD6EBE8C160.dita"><apiname>CCoeControl</apiname></xref>)</p>
</li>
</ol>
<section id="GUID-B8AA011F-23EB-4BA5-9FA6-1382D37E13A9"><title>Entry point</title>
<p>The two methods that you need to implement for the entry point are as
follows:</p>
<ul>
<li><p>an entry point for the application, with the following syntax:</p>
<itemgroup>
<codeblock id="GUID-F09C226F-B1D6-4435-8983-7DD62D1BBD26" xml:space="preserve">GLDEF_C TInt E32Main()
    {
    return EikStart::RunApplication( NewApplication );
    }</codeblock>
<p>where:</p>
<p><parmname>E32Main()</parmname> is the entry point method called by the
application framework</p>
<p><parmname>return EikStart::RunApplication(NewApplication )</parmname> calls<xref href="GUID-E5533B10-D01F-3133-8E74-28071766885B.dita#GUID-E5533B10-D01F-3133-8E74-28071766885B/GUID-275C4B9B-53BD-38C5-8C8E-05D480358836"><apiname> EikStart::RunApplication()</apiname></xref></p>
</itemgroup>
</li>
<li><p>a non-leaving factory method that creates a new instance
of the application class, or <parmname>NULL</parmname> if the class cannot
be instantiated. The expected syntax is as follows:</p>
<itemgroup>
<codeblock id="GUID-D1F8BE18-84A5-4F32-9BC8-D5458455492A" xml:space="preserve">LOCAL_C CApaApplication* NewApplication()
    {
    return new CMyAppClass;
    }</codeblock>
<p>where:</p>
<p><parmname>NewApplication()</parmname> is a method that returns a pointer
to a <xref href="GUID-C0297A58-2E39-3211-A2B4-C334192CE2A7.dita"><apiname>CApaApplication</apiname></xref> object.</p>
<p><parmname>return new CMyAppClass</parmname> returns an instance of the
application class as created by the <xref href="GUID-4F825D83-47A4-36C9-9A25-943A6D799F84.dita"><apiname>CAknApplication</apiname></xref> derived
class</p>
<p>The application framework expects the factory method to have exactly
this prototype. In other words, the factory function should be like the above
code fragment.</p>
</itemgroup>
</li>
</ul>
</section>
<section id="GUID-63C94373-F55D-4B58-9637-7BA0E1B14ACF"><title>CAknApplication</title>
<p>You must implement at least the following two methods in your <xref href="GUID-4F825D83-47A4-36C9-9A25-943A6D799F84.dita"><apiname>CAknApplication</apiname></xref> derived
class:</p>
<ul>
<li><p>a method that returns the application UID. The syntax is
as follows:</p>
<codeblock id="GUID-77921F31-5A36-4A6B-AD2C-E9364A50E0F6" xml:space="preserve">TUid CMyAppClass::AppDllUid() const
    {
    return KUidMyApp;
    }</codeblock>
<p>where:</p>
<itemgroup>
<p><xref href="GUID-C0297A58-2E39-3211-A2B4-C334192CE2A7.dita#GUID-C0297A58-2E39-3211-A2B4-C334192CE2A7/GUID-669C19DC-04C9-3979-A87E-8F9EFA8E4D99"><apiname>CApaApplication::AppDllUid()</apiname></xref> is used to get the application
UID</p>
<p><parmname>KUidMyApp</parmname> is the UID for your application, which
is typically declared in an application header file.</p>
</itemgroup>
<p>The application framework calls the <parmname>AppDllUid()</parmname> method
to get the application UID. The application framework checks to see if there
is an instance of the application with the same UID already running. If so,
then the application framework switches to the already existing application. </p>
<note>
<p>You must return the same UID that you declared for the UID3 in the <xref href="GUID-1F7E1476-D7A3-49E4-B05B-F3A0FD6333B6.dita"><parmname>mmp</parmname></xref> and <xref href="GUID-FE9017F4-4197-472F-A3E7-267169A51ABD.dita">registration</xref> files.</p>
</note>
</li>
<li><p>a factory function for creating an object of the document
class for your application. The expected syntax is as follows:</p>
<codeblock id="GUID-C56EAA45-A671-47D6-8FE6-492B154813BF" xml:space="preserve">CApaDocument* CMyAppClass::CreateDocumentL()
    {
    return CMyAppDocument::NewL( *this );
    }
</codeblock>
<p>where:</p>
<itemgroup>
<p><xref href="GUID-E36E2F07-09E7-32BC-BB83-14DF9232E7D9.dita#GUID-E36E2F07-09E7-32BC-BB83-14DF9232E7D9/GUID-D0810109-8F11-3B65-8806-9A61317D2128"><apiname>CEikApplication::CreateDocumentL()</apiname></xref> is called by the
application framework.</p>
<p> <parmname>return CMyAppDocument::NewL( *this )</parmname> returns an
instance of the <xref href="GUID-935C59EE-AD66-33FE-987B-BD97F5147CC1.dita"><apiname>CAknDocument</apiname></xref> derived class of your application.
It represents the data that relates to a particular instance of the application
and owns the application <xref href="GUID-FD2CDEB8-0784-4BE5-A775-170F57D71BBC.dita">UI
controller</xref>.</p>
</itemgroup>
</li>
</ul>
<note>
<p>The application framework owns the document object and is responsible
for destroying it.</p>
</note>
</section>
<section id="GUID-73A8D2EE-F22A-483D-A23A-5E46D709A718"><title>CAknDocument</title>
<p>You must implement a <xref href="GUID-935C59EE-AD66-33FE-987B-BD97F5147CC1.dita"><apiname>CAknDocument</apiname></xref> derived class for
your application, even if you do not store data, as this is the class that
owns the <xref href="GUID-FD2CDEB8-0784-4BE5-A775-170F57D71BBC.dita">UI controller</xref> for
your application. The expected syntax for creating the UI controller class
is as follows:</p>
<codeblock id="GUID-C016DB83-2B28-4DEC-8027-A9291E380191" xml:space="preserve">CEikAppUi* CMyAppDocument::CreateAppUiL()
    {
    return new ( ELeave ) CMyAppAppUi;
    }</codeblock>
<p>where:</p>
<ul>
<li><p><xref href="GUID-B33A8A56-D1BE-3E3D-B5AC-F644A5C764DB.dita#GUID-B33A8A56-D1BE-3E3D-B5AC-F644A5C764DB/GUID-37544F28-FD9A-3E11-96B8-7DA8BC84CC59"><apiname>CEikDocument::CreateAppUiL()</apiname></xref> carries out
the first phase construction of the UI controller</p></li>
<li><p><parmname>new ( ELeave ) CMyAppAppUi </parmname> is a method
that creates an instance of the UI controller class of your application</p>
</li>
</ul>
<p>The application framework owns the UI controller object of the application
and is responsible for destroying it. There are two alternate classes from
which you can derive your UI controller class, <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita"><apiname>CAknAppUi</apiname></xref> or <xref href="GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E.dita"><apiname>CAknViewAppUi</apiname></xref>.</p>
<p>For more information on the UI controller options, see <xref href="GUID-FD2CDEB8-0784-4BE5-A775-170F57D71BBC.dita">UI controller</xref></p>
</section>
</conbody></concept>