SimpleXMLIterator在SimpleXMLElement对象的所有节点上提供递归迭代。 ## 方法： ``` class SimpleXMLElement implements Traversable { /* 方法 */ public __construct( string $data, int $options = 0, bool $dataIsURL = false, string $namespaceOrPrefix = "", bool $isPrefix = false ) public addAttribute(string $qualifiedName, string $value, ?string $namespace = null): void public addChild(string $qualifiedName, ?string $value = null, ?string $namespace = null): ?SimpleXMLElement public asXML(?string $filename = null): string|bool public attributes(?string $namespaceOrPrefix = null, bool $isPrefix = false): ?SimpleXMLElement public children(?string $namespaceOrPrefix = null, bool $isPrefix = false): ?SimpleXMLElement public count(): int public getDocNamespaces(bool $recursive = false, bool $fromRoot = true): array|false public getName(): string public getNamespaces(bool $recursive = false): array public registerXPathNamespace(string $prefix, string $namespace): bool public __toString(): string public xpath(string $expression): array|null|false } ```