什么PHP代码访问迭代器接口等同于foreach循环？

class MyIterator implements Iterator {
    private $position = 0;
    private $array = ['apple', 'banana', 'orange'];

    public function __construct() {
        $this->position = 0;
    }

    public function rewind() {
        $this->position = 0;
    }

    public function current() {
        return $this->array[$this->position];
    }

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

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

    public function valid() {
        return isset($this->array[$this->position]);
    }
}

$iterator = new MyIterator();

foreach ($iterator as $key => $value) {
    echo $key . ': ' . $value . "\n";
}