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<concept id="GUID-FD2CDEB8-0784-4BE5-A775-170F57D71BBC" xml:lang="en"><title>UI controller</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The term <i>UI controller</i> refers to an object derived from either <parmname>CAknAppUi</parmname> or <parmname>CAknViewAppUi</parmname>,

depending on your UI architecture. The UI controller is a required part of

GUI-based applications.</p>

<p>Examples of services and responsibilities provided by the UI controller

are as follows:</p>

<ul>

<li><p>control stack for <xref href="GUID-A9330FEF-C559-4E2B-B064-0151FDADEA8C.dita">event

handling</xref></p></li>

<li><p>construction of <xref href="GUID-DAC32BB9-C0EB-42FF-A596-C2F1A90A4BD7.dita">views</xref> for

applications</p></li>

<li><p>the top-level window owning <xref href="GUID-5944FFF1-79C6-4F5E-95C8-F4833AFC64AB.dita">control</xref> of

the application</p></li>

</ul>

<p>For more information on the UI controller, see:</p>

<ul>

<li><p><xref href="GUID-BBC374AD-88E6-5C58-88BB-B939C2948DDA.dita">The

Application User Interface</xref></p></li>

<li><p><xref href="GUID-E244744F-4837-5B46-8E37-4666A28BF0B7.dita">The

run-time control hierarchy</xref></p></li>

</ul>

<p>The UI controller is part of the controller structure in the Model -

View - Controller <xref href="GUID-BDDDF68F-F7C3-43AF-8B6C-C77C701FD2A9.dita">(MVC)

design pattern</xref> used to design the architecture of many GUI-based mobile

applications.</p>

<p>The <xref href="GUID-07D2ED79-90B2-4ABC-A61F-108DAEE21955.dita"><parmname>CAknDocument</parmname></xref> -derived

class of your application contains the <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/guide/Base-subsystem-guide/e32/MemoryManagement/CleanupSupport/CleanupSupportGuide3/index.html#CleanupSupportGuide3%2etoc" format="application/java-archive">first

phase</xref> constructor of the UI controller.</p>

<note>

<p>The second-phase constructor is called by the application framework.</p>

</note>

<p>The UI controller is implemented in one of the following classes:</p>

<ul>

<li><p>In a <xref href="GUID-B5DE1C86-2B16-4B22-887F-7079E54A8ED6.dita">traditional

architecture</xref> application architecture, the UI controller must be derived

from <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita"><apiname>CAknAppUi</apiname></xref>.</p></li>

<li><p>In <xref href="GUID-68B999C2-0993-4804-9624-42C3D88BE5C7.dita">Symbian

view architecture</xref>, the UI controller must be derived from <xref href="GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E.dita"><apiname>CAknViewAppUi</apiname></xref>.</p>

</li>

<li><p>In <xref href="GUID-DD88DD7B-E246-4BF2-B537-5C677728CC49.dita">dialog

architecture</xref>, the UI controller is typically derived from <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita"><apiname>CAknAppUi</apiname></xref>.</p>

</li>

</ul>

</conbody></concept>