Full code below ...

#include "HelloWorld.h"

CDelayedHello* CDelayedHello::NewL()
{
   CDelayedHello* self = new (ELeave) CDelayedHello();
   CleanupStack::PushL(self);
   self->ConstructL;
   CleanupStack::Pop(self);
   return self;
}

CDelayedHello::~CDelayedHello()
{
   Cancel();
   iTimer.Close();
}

void CDelayedHello::SetHello(TTimeIntervalMicroSeconds32 aDelay)
{
   _LIT(KDelayedHelloPanic, "DelayedHelloPanic");
   __ASSERT_ALWAYS(!IsActive(), User::Panic(KDelayedHelloPanic, 1));
   iTimer.After(iStatus, aDelay);
   SetActive();
}

CDelayedHello::CDelayedHello() : CActive(CActive::EPriorityStandard)
{
   CActiveScheduler::Add(this);
}

void CDelayedHello::ConstructL()
{
   iEnv = CEikonEnv::Static();
   User::LeaveIfError(iTimer.CreateLocal());
}

void CDelayedHello::RunL()
{
   iEnv->InfoMsg(R_DELAYED_HELLO_TEXT);   
}

void CDelayedHello::DoCancel()
{
   iTimer.Cancel();
}

TInt CDelayedHello::RunError(TInt aError)
{
   return KErrNone;
}