Introduction.md

Introduction

An XML writer is a tool for producing XML documents. Although XML is a simple, textual format, it does have its pitfalls.

Production quality code should always use an XML writer directly or indirectly.

The only exception is if your XML format is super-simple and you know how to do XML encoding, which you probably don't.

XML serializer API

There is two protocols to choose from, one with namespace support and one without. For special needs, use the base interface.

XMLStreamWriter

For serialization of XML without namespaces.

// allocate serializer
id<XMLStreamWriter> xmlWriter = [[XMLWriter alloc]init];

// start writing XML elements
[xmlWriter writeStartElement:@"Root"];
[xmlWriter writeCharacters:@"Text content for root element"];
[xmlWriter writeEndElement];

produces the following XML:

<Root>Text content for root element</Root>

NSXMLStreamWriter

For serialization of XML with namespaces.

// allocate serializer
id<NSXMLStreamWriter> xmlWriter = [[XMLWriter alloc]init];
 
// set necessary namespace(s) and prefix(es)
[xmlWriter setPrefix:@"abc" namespaceURI:@"urn:my:namespace:uri"];

// start writing XML elements with namespaces
[xmlWriter writeStartElementWithNamespace:"urn:my:namespace:uri" localName:@"Root"];
[xmlWriter writeCharacters:@"Text content for root element with namespace"];
[xmlWriter writeEndElement];

produces the following XML:

<abc:Root xmlns:abc="urn:my:namespace:uri">Text content for root element with namespace</abc:Root>

You may write any XML document using this serializer. For further examples, see this wiki page.