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);
    }
}

运行

$obj = new myData;

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

输出

string(9) "property1"
string(19) "Public property one"

string(9) "property2"
string(19) "Public property two"

string(9) "property3"
string(21) "Public property three"

string(9) "property4"
string(13) "last property"