public function offsetGet($index)
    {
        if (is_string($index) && isset($this->_keysMap[$index])) {
            $index = $this->_keysMap[$index];
        }

        return parent::offsetGet($index);
    }
public function offsetGet($index)
    {
        if (is_string($index) && isset($this->_keysMap[$index])) {
            $index = $this->_keysMap[$index];
        }

        return parent::offsetGet($index);
    }
public function offsetGet ( $ index ) { if ( is_string ( $ index ) && isset ( $ this -> _keysMap [ $ index ] ) ) { $ index = $ this -> _keysMap [ $ index ] ; } return parent :: offsetGet ( $ index ) ; }
Allows access fields by numeric index or by machine-name.

### Example:

```php
$fields => [
[0] => [
[name] => user-age,
[label] => User Age,
[value] => 22,
[extra] => null,
[metadata] => [ ... ]
],
[1] => [
[name] => user-phone,
[label] => User Phone,
[value] => null,
[extra] => null,
[metadata] => [ ... ]
]
];

$collection = new FieldCollection($fields);
if ($collection[1] === $collection['user-phone']) {
echo "SUCCESS";
}

// outputs: SUCCESS
```

@param int|string $index Numeric index or machine-name
@return mixed \Field\Model\Entity\Field on success or NULL on failure
Allows access fields by numeric index or by machine - name .