Iterator.php

<?php
class sample implements Iterator {
    private $_items ;

    public function __construct(&$data) {
        $this->_items = $data;
    }
    public function current() {
        return current($this->_items);
    }

    public function next() {
        next($this->_items);
    }

    public function key() {
        return key($this->_items);
    }

    public function rewind() {
        reset($this->_items);
    }

    public function valid() {
        return ($this->current() !== FALSE);
    }
}

// client
$data = array(1, 2, 3, 4, 5);
$sa = new sample($data);
foreach ($sa AS $key => $row) {
    echo $key, ' ', $row, '<br />';
}
//Yii FrameWork Demo
class CMapIterator implements Iterator {
    /**
     * @var array the data to be iterated through
     */
    private $_d;
    /**
     * @var array list of keys in the map
     */
    private $_keys;
    /**
     * @var mixed current key
     */
    private $_key;

    /**
     * Constructor.
     * @param array the data to be iterated through
     */
    public function __construct(&$data) {
        $this->_d=&$data;
        $this->_keys=array_keys($data);
    }

    /**
     * Rewinds internal array pointer.
     * This method is required by the interface Iterator.
     */
    public function rewind() {
        $this->_key=reset($this->_keys);
    }

    /**
     * Returns the key of the current array element.
     * This method is required by the interface Iterator.
     * @return mixed the key of the current array element
     */
    public function key() {
        return $this->_key;
    }

    /**
     * Returns the current array element.
     * This method is required by the interface Iterator.
     * @return mixed the current array element
     */
    public function current() {
        return $this->_d[$this->_key];
    }

    /**
     * Moves the internal pointer to the next array element.
     * This method is required by the interface Iterator.
     */
    public function next() {
        $this->_key=next($this->_keys);
    }

    /**
     * Returns whether there is an element at current position.
     * This method is required by the interface Iterator.
     * @return boolean
     */
    public function valid() {
        return $this->_key!==false;
    }
}

$data = array('s1' => 11, 's2' => 22, 's3' => 33);
$it = new CMapIterator($data);
foreach ($it as $row) {
    echo $row, '<br />';
}