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# replacementClass(for:)

Overridden by subclasses to substitute a custom class for an NSXML class that the parser uses to create node instances.

```
class func replacementClass(for cls: AnyClass) -> AnyClass
```

## Parameters

`cls`

A `Class` object identifying an NSXML class that is to be replaced by your custom class.

## Return Value

The substituted class.

## Discussion

For example, if you have a custom subclass of [`XMLElement`](/documentation/Foundation/XMLElement) that you want to be used in place of `NSXMLElement`, you would make the following override:

```objc
+ (Class)replacementClassForClass:(Class)currentClass {
    if ( currentClass == [NSXMLElement class] ) {
        return [MyCustomElementClass class];
    }
}
```

This method is invoked before a document is parsed. The substituted class must be a subclass of [`XMLNode`](/documentation/Foundation/XMLNode), `NSXMLDocument`, `NSXMLElement`, [`XMLDTD`](/documentation/Foundation/XMLDTD), or [`XMLDTDNode`](/documentation/Foundation/XMLDTDNode).

## See Also

[`setRootElement(_:)`](/documentation/Foundation/XMLDocument/setRootElement(_:))

Set the root element of the receiver.


---

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