class MainIterator implements Iterator
{
    private $var = array();
    public function __construct($array)    //构造函数, 初始化对象数组
    {
        if (is_array($array)) {
        $this->var = $array;
        }
    }
 
    public function rewind() {   
        echo "rewinding\n";
        reset($this->var);    //将数组的内部指针指向第一个单元
    }
 
    public function current() {
        $var = current($this->var);    // 返回数组中的当前值
        echo "current: $var\n";
        return $var;
    }
 
    public function key() {
        $var = key($this->var);       //返回数组中内部指针指向的当前单元的键名
        echo "key: $var\n";
        return $var;
    }
 
    public function next() {
        $var = next($this->var);     //返回数组内部指针指向的下一个单元的值
        echo "next: $var\n";
        return $var;
    }
 
    public function valid() {
    return !is_null(key($this->var); //判断当前单元的键是否为空
    }
}

?php
class myData implements IteratorAggregate {
    public $property1 = "Public property one";
    public $property2 = "Public property two";
    public $property3 = "Public property three";

    public function __construct() {
        $this->property4 = "last property";
    }

    public function getIterator() {
        return new ArrayIterator($this);
    }
}

$obj = new myData;

foreach($obj as $key => $value) {
    var_dump($key, $value);
    echo "\n";
}
?>