如何将变量从控制器传递到视图以及如何根据我在CodeIgniter中获得的变量显示视图？

I am passing the data from the controller to view with the variable value but in my view, I have two forms and I want to display the form according to the variable data I have. I tried using if(isset$_GET[]) method but it doesn't work. Below is my code. Please rectify me where I am doing the mistake.

public function epacat($pa_cat_id)
{ 
  $this->top();
  $data['pa_cat'] = $this->adata->parentCategories();

  //BELOW I AM PASSING DATA
  $data['epa_cat'] = $this->adata->epacatQ($pa_cat_id);
  $this->load->view('am/parent-categories/parent_categories',$data);
  $this->bottom();
}

<div class="row">
  //WANT TO DISPLAY IF I GOT VARIABLE
  <?php if(isset(['epacat'])):?>
    <div class="col-md-12">
      <?php echo form_open('admin/apacat');?>
      <label><h4>Update Parent Category</h4></label>
      <?php echo form_input(['name'=>'pa_cat_name','class'=>'form-control','placeholder'=>'Enter your parent category','value'=>set_value('pa_cat_name',$pc->pa_cat_name)]);?>
      <button type="reset" class="btn btn-warning">Reset</button> <button type="submit" class="btn btn-primary">Submit</button>
     <?php form_close();?>
    </div>

   //WANT TO DISPLAY IF I NOT GOT VARIABLE
  <?php else:?>
    <div class="col-md-12">
      <?php echo form_open('admin/apacat');?>
      <label><h4>Add Parent Category</h4></label>
      <?php echo form_input(['name'=>'pa_cat_name','class'=>'form-control','placeholder'=>'Enter your parent category','value'=>set_value('pa_cat_name')]);?>
      <button type="reset" class="btn btn-warning">Reset</button> <button type="submit" class="btn btn-primary">Submit</button>
      <?php form_close();?>
    </div>
  <?php endif;?>
</div>

You're doing it correctly in the controller

$data['epa_cat'] = $this->adata->epacatQ($pa_cat_id);
$this->load->view('am/parent-categories/parent_categories',$data);

In the view, $data['epa_cat'] becomes $epa_cat.

So for example, if $epa_cat is a string you'd do

<p><?php echo $epa_cat; ?></p>

Or if $epa_cat is a boolean, you could check it like so

if ($epa_cat) {
    // Do stuff
}

You can write like this

public function epacat($pa_cat_id)
{ 
$this->top();
$data['pa_cat'] = $this->adata->parentCategories();

//BELOW I AM PASSING DATA
$data['epa_cat'] = $this->adata->epacatQ($pa_cat_id);
$this->load->view('am/parent-categories/parent_categories',$data);
$this->bottom();
}

<div class="row">
//WANT TO DISPLAY IF I GOT VARIABLE
<?php if($epacat):?>
<div class="col-md-12">
<?php echo form_open('admin/apacat');?>
<label><h4>Update Parent Category</h4></label>
<?php echo form_input(['name'=>'pa_cat_name','class'=>'form-control','placeholder'=>'Enter your parent category','value'=>set_value('pa_cat_name',$pa_cat->pa_cat_name)]);?>
<button type="reset" class="btn btn-warning">Reset</button> <button type="submit" class="btn btn-primary">Submit</button>
<?php form_close();?>
</div>

//WANT TO DISPLAY IF I NOT GOT VARIABLE
<?php else:?>
<div class="col-md-12">
<?php echo form_open('admin/apacat');?>
<label><h4>Add Parent Category</h4></label>
<?php echo form_input(['name'=>'pa_cat_name','class'=>'form-control','placeholder'=>'Enter your parent category','value'=>set_value('pa_cat_name')]);?>
<button type="reset" class="btn btn-warning">Reset</button> <button type="submit" class="btn btn-primary">Submit</button>
<?php form_close();?>
</div>
<?php endif;?>

</div>

Just for fun ( and not tested )

Use the one block of HTML and derive the bits that are different depending upon $epa_cat

<?php
if($epa_cat){
    $label = 'Update';
    $value = set_value('pa_cat_name', $pc->pa_cat_name);
} else {
    $label = 'Add';
    $value = set_value('pa_cat_name');
}
?>
<div class="row">
    <div class="col-md-12">
        <?= form_open('admin/apacat'); ?>
        <label><h4><?=$label;?> Parent Category</h4></label>
        <?= form_input(['name' => 'pa_cat_name', 'class' => 'form-control', 'placeholder' => 'Enter your parent category', 'value' => $value]); ?>
        <button type="reset" class="btn btn-warning">Reset</button>
        <button type="submit" class="btn btn-primary">Submit</button>
        <?php form_close(); ?>
    </div>
</div>

Still not sure where $pc->pa_cat_name comes from, but with what was provided, this would be a first attempt.

I also changed <?php echo to <?= as a demonstration that can be used.