---
title: validate()
framework: foundation
role: symbol
role_heading: Instance Method
path: foundation/xmldocument/validate()
---

# validate()

Validates the document against the governing schema and returns whether the document conforms to the schema.

## Declaration

```swift
func validate() throws
```

## Discussion

Discussion The constants indicating the kind of validation errors are emitted by the underlying parser; see NSXMLParser.h for most of these constants. If the schema is defined with a DTD, this method uses the XMLDTD object set for the receiver for validation. If the schema is based on XML Schema, the method uses the URL specified as the value of the xsi:schemaLocation attribute of the root element. You can validate an XML document when it is first processed by specifying the NSXMLDocumentValidate option when you initialize an NSXMLDocument object with the init(contentsOf:options:), init(data:options:), or init(xmlString:options:) methods. note: In Swift, this method returns Void and is marked with the throws keyword to indicate that it throws an error in cases of failure. You call this method in a try expression and handle any errors in the catch clauses of a do statement, as described in Error Handling in The Swift Programming Language and About Imported Cocoa Error Parameters.