Modern, simplified SMXMLDocument

SMXMLDocument.h

/*
 The MIT License
 
 Copyright (c) 2011 Spotlight Mobile
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE. 
*/

// SMXMLDocument is a very handy lightweight XML parser for iOS.

extern NSString *const SMXMLDocumentErrorDomain;

@interface SMXMLElement : NSObject

@property (nonatomic, assign, readonly) SMXMLElement *parent;
@property (nonatomic, copy, readonly) NSString *name;
@property (nonatomic, readonly) NSString *value;
@property (nonatomic, readonly) NSArray *children;
@property (nonatomic, strong, readonly) NSDictionary *attributes;
@property (nonatomic, readonly) SMXMLElement *firstChild;
@property (nonatomic, readonly) SMXMLElement *lastChild;

+ (SMXMLElement *)rootElementForData:(NSData *)data;
+ (SMXMLElement *)rootElementForData:(NSData *)data error:(NSError **)error;

- (id)childrenWithValue:(NSString *)name forAttribute:(NSString *)value;

@end

SMXMLDocument.m

#import "SMXMLDocument.h"

NSString *const SMXMLDocumentErrorDomain = @"SMXMLDocumentErrorDomain";

static NSError *SMXMLDocumentError(NSXMLParser *parser, NSError *parseError) {	
	NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithObject:parseError forKey:NSUnderlyingErrorKey];
	NSNumber *lineNumber = [NSNumber numberWithInteger:parser.lineNumber];
	NSNumber *columnNumber = [NSNumber numberWithInteger:parser.columnNumber];
	[userInfo setObject:[NSString stringWithFormat:NSLocalizedString(@"Malformed XML document. Error at line %@:%@.", @""), lineNumber, columnNumber] forKey:NSLocalizedDescriptionKey];
	[userInfo setObject:lineNumber forKey:@"LineNumber"];
	[userInfo setObject:columnNumber forKey:@"ColumnNumber"];
	return [NSError errorWithDomain:SMXMLDocumentErrorDomain code:1 userInfo:userInfo];
}

@interface SMXMLElement() <NSXMLParserDelegate> {
	NSMutableString *value;
	NSMutableArray *children;
}
@property (nonatomic, assign) SMXMLElement *root;
@property (nonatomic, assign, readwrite) SMXMLElement *parent;
@property (nonatomic, copy, readwrite) NSString *name;
@property (nonatomic, strong, readwrite) NSDictionary *attributes;
@property (nonatomic, strong) NSError *error;
@end

@implementation SMXMLElement

@synthesize parent, name, value, children, attributes, root, error;

+ (SMXMLElement *)rootElementForData:(NSData *)data {
    return [self rootElementForData:data error:NULL];
}

+ (SMXMLElement *)rootElementForData:(NSData *)data error:(NSError **)error {
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
    SMXMLElement *root = [SMXMLElement new];
    parser.delegate = root;
    parser.shouldProcessNamespaces = YES;
    parser.shouldReportNamespacePrefixes = YES;
    parser.shouldResolveExternalEntities = NO;
    BOOL success = [parser parse];
    if (!success) {
        if (error)
            *error = parser.parserError;
        return nil;
    }
    return root;
}

- (NSString *)descriptionWithIndent:(NSString *)indent {
	NSMutableString *s = [NSMutableString string];
    
	[s appendFormat:@"%@<%@", indent, name];
    
    [attributes enumerateKeysAndObjectsUsingBlock:^(NSString *attribute, id attribValue, BOOL *stop) {
        [s appendFormat:@" %@=\"%@\"", attribute, attribValue];
    }];

	NSString *trimVal = [value stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

	if (trimVal.length > 25)
		trimVal = [NSString stringWithFormat:@"%@…", [trimVal substringToIndex:25]];
	
	if (children.count) {
		[s appendString:@">\n"];
		
		NSString *childIndent = [indent stringByAppendingString:@"  "];
		
		if (trimVal.length)
			[s appendFormat:@"%@%@\n", childIndent, trimVal];

		for (SMXMLElement *child in children)
			[s appendFormat:@"%@\n", [child descriptionWithIndent:childIndent]];
		
		[s appendFormat:@"%@</%@>", indent, name];
	} else if (trimVal.length)
		[s appendFormat:@">%@</%@>", trimVal, name];
	else [s appendString:@"/>"];
	
	return s;	
}

- (NSString *)description {
	return [self descriptionWithIndent:@""];
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
    if (value)
        [value appendString:string];
    else
        value = [string mutableCopy];
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
    if (self.name || self.attributes) {
        SMXMLElement *child = [SMXMLElement new];
        child.root = self.root ? self.root : self;
        child.parent = self;
        child.name = elementName;
        child.attributes = attributeDict;
        parser.delegate = child;
        if (children)
            [children addObject:child];
        else
            children = [[NSMutableArray alloc] initWithObjects:child, nil];
    } else {
        self.name = elementName;
        self.attributes = attributeDict;
    }
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
    parser.delegate = parent;
}

- (void)parserDidEndDocument:(NSXMLParser *)parser {
    parser.delegate = nil;
}

- (id)valueForKey:(NSString *)key {
    if ([key isEqualToString:@"@attributes"])
        return attributes;
    
    NSIndexSet *indexes = [children indexesOfObjectsPassingTest:^BOOL(SMXMLElement *child, NSUInteger idx, BOOL *stop) {
        return ([child.name isEqual:key]);
    }];
    
    if (indexes.count == 1) {
        SMXMLElement *element = [children objectAtIndex:[indexes firstIndex]];
        if (element.children.count)
            return element;
        else
            return element.value;
    } else {
        NSArray *elements = [children objectsAtIndexes:indexes];
        return [elements valueForKey:key];
    }
    
    return nil;
}

- (id)valueForKeyPath:(NSString *)keyPath {
    NSRange attribRange = [keyPath rangeOfString:@"@attributes"];
    if (attribRange.location == NSNotFound)
        return [super valueForKeyPath:keyPath];
    else {
        NSString *newKeyPath = [keyPath substringToIndex:NSMaxRange(attribRange)];
        NSString *newDictKeyPath = [keyPath substringFromIndex:NSMaxRange(attribRange)];
        id result = [super valueForKeyPath:newKeyPath];
        return [result valueForKeyPath:newDictKeyPath];
    }
}

- (id)childrenWithValue:(NSString *)testName forAttribute:(NSString *)testValue {
    NSString *keyPath = [NSString stringWithFormat:@"@attributes.%@", testValue];
    NSIndexSet *indexes = [children indexesOfObjectsPassingTest:^BOOL(SMXMLElement *child, NSUInteger idx, BOOL *stop) {
        return [[child valueForKeyPath:keyPath] isEqualToString:testName];
    }];
    
    if (!indexes.count)
        return nil;
    
    if (indexes.count == 1)
        return [children objectAtIndex:[indexes firstIndex]];
    else
        return [children objectsAtIndexes:indexes];
}

- (SMXMLElement *)firstChild {
    return children.count ? [children objectAtIndex:0] : nil;
}

- (SMXMLElement *)lastChild {
    return [children lastObject];
}

@end