Object Creation With XML

KTObjectLoader.h

#import <Foundation/Foundation.h>

@interface KTObjectLoader : NSObject<NSXMLParserDelegate>

+ (NSArray *)loadObjectsFromURL:(NSURL *)url;
+ (NSArray *)loadObjectsFromData:(NSData *)data;

@end

KTObjectLoader.m

#import "KTObjectLoader.h"

#define kRootElement	@"root"

@interface KTXMLParser : NSXMLParser

@property (assign) NSUInteger state;
@property (assign) NSMutableArray *objects;

@end

@implementation KTXMLParser

@synthesize state = _state;
@synthesize objects = _objects;

@end


@implementation KTInterfaceLoader

static
id _createInstance(NSString *className,NSDictionary *attributes,SEL _cmd) {
	Class klass = NSClassFromString(className);
	id obj = nil;
	if (klass) {
		
		obj = [klass alloc];
		if ([obj respondsToSelector:@selector(initWithAttributes:)]) {
			obj = [obj performSelector:@selector(initWithAttributes:) withObject:attributes];
		} else {
			NSLog(@"A instance of class %@ not responds to selector initWithAttributes:",className);
			[obj release];
			obj = nil;
		}
	} else {
		NSLog(@"Unknown class:%@",className);
	}
	return obj;
}

- (void)parser:(KTXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
	switch (parser.state) {
		case 0:
			if (![elementName isEqualToString:kRootElement]) {
				NSLog(@"The document starts with unknown element %@",elementName);
				[parser abortParsing];
			}
			break;
		case 1:
			{
				id obj = _createInstance(elementName, attributeDict,_cmd);
				if (obj) {
					[parser.objects addObject:obj];
					[obj release];
				} else {
					NSLog(@"Instance creation failure");
					[parser abortParsing];
				}
			}
			break;
		default:
			NSLog(@"Invalid document structure");
			[parser abortParsing];
	}
	parser.state += 1;
}

- (void)parser:(KTXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
	parser.state -= 1;	
}

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
	NSLog(@"%@",parseError);
}

static
NSArray *_parseWithParser(KTXMLParser *parser) {
	[parser setShouldProcessNamespaces:NO];
	[parser setShouldReportNamespacePrefixes:NO];
	[parser setShouldResolveExternalEntities:NO];	
	
	parser.objects = [NSMutableArray array];
	
	if ([parser parse]) {
		NSLog(@"load success");
		return parser.objects;
	}
	return nil;
}

- (NSArray *)loadObjectsFromURL:(NSURL *)url {
	KTXMLParser *parser = [[[KTXMLParser alloc] initWithContentsOfURL:url] autorelease];
	parser.delegate = self;
	return _parseWithParser(parser);
}

- (NSArray *)loadObjectsFromData:(NSData *)data {
	KTXMLParser *parser = [[[KTXMLParser alloc] initWithData:data] autorelease];
	parser.delegate = self;
	return _parseWithParser(parser);
}

+ (NSArray *)loadObjectsFromURL:(NSURL *)url {
	return [[[[KTObjectLoader alloc] init] autorelease] loadObjectsFromURL:url];
}

+ (NSArray *)loadObjectsFromData:(NSData *)data {
	return [[[[KTObjectLoader alloc] init] autorelease] loadObjectsFromData:data];
}

@end