XML Parsing in iPhone

I am new in xml parsing.I am totaly cofused how many methods we should have to require for xml parsing and what does use of that method.I want to send开发者_如何学Python input to the webservied and by use of xml parsing i want to display result in my text field.

See this questions for resources on how to pick an XML parser for your iOS application:

Choosing the right IOS XML parser

I choose TouchXML for my projects. It is a DOM parser and has XPath support:

https://github.com/TouchCode/TouchXML

You should use the following methods:

- (void)parseXMLFileAtURL:(NSString *)URL { //own method from me, URL could be local file or internet website 
    itemsOfFeed = [[NSMutableArray alloc] init];
    NSURL *xmlURL = [NSURL URLWithString:URL];
    feedParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];
    [feedParser setDelegate:self];
    [feedParser setShouldProcessNamespaces:NO];
    [feedParser setShouldReportNamespacePrefixes:NO];
    [feedParser setShouldResolveExternalEntities:NO];
    [feedParser parse];
}

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
    //in case of an error
}

- (void)parserDidStartDocument:(NSXMLParser *)parser {
    // start to parse xml
}

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
    feedElement = [elementName copy];
    if([elementName isEqualToString:@"item"]) { //main xml tag
        item = [[NSMutableDictionary alloc] init];
        feedTitle = [[NSMutableString alloc] init];
        feedDate = [[NSMutableString alloc] init];
        feedText = [[NSMutableString alloc] init];
        feedLink = [[NSMutableString alloc] init];
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
    if([feedElement isEqualToString:@"title"]) {
        [feedTitle appendString:string];
    } else if([feedElement isEqualToString:@"link"]) { // some examples of tags
        [feedLink appendString:string];
    } else if([feedElement isEqualToString:@"content:encoded"]) {
        [feedText appendString:string];
    } else if([feedElement isEqualToString:@"pubDate"]) {
        [feedDate appendString:string];
    }
}

- (void) parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
    if([elementName isEqualToString:@"item"]) {
        [item setObject:feedTitle forKey:@"title"];
        [item setObject:feedDate forKey:@"date"];
        [item setObject:feedText forKey:@"text"];       
        [item setObject:feedLink forKey:@"link"];
        [itemsOfFeed addObject:item];
    }
}

- (void)parserDidEndDocument:(NSXMLParser *)parser {
    [self.myTableView reloadData]; // for example reload table view
    [self writeArrayToFile]; //or write to a local property list
}

in your header file:

NSMutableArray *itemsOfFeed;
NSXMLParser *feedParser;
NSMutableDictionary *item;
NSMutableString *feedElement;
NSMutableString *feedTitle, feedDate, feedText, feedLink; //strings of your tags

Then you have:

• NSArray
  • NSDictionary
    • object a
    • object b
    • object c

Just access 'object a' and put it in your text field

hopefully this code example helps you

Here is the very helpful tutorial.

http://www.edumobile.org/iphone/iphone-programming-tutorials/parsing-an-xml-file/

Hi I would personally prefer to use NSXMLParser.

Write your own code which uses NSXMLParserDelegate methods implementation.

But still there are some third party libraries available. Here is a nice example to compare how all those parser differs from each other and also having nice explanation. Code is also available over there.

Hope this will be helpful to you.

-Mrunal

i have a demo app for parsing static XML to UITableView, I think this one will surely will help you.

Availiable third party libraries available below, depend on developer choice this, which is best?

• NSXMLParser
• libxml2
• TBXMLParser
• TouchXMLParser
• KissXMLParser
• TinyXMLParser
• GDataXMLParser

And you can also get more information from this great tutorial link http://www.raywenderlich.com/553/how-to-chose-the-best-xml-parser-for-your-iphone-project

Try this:

XMLReader.h

//
//  XMLReader.h
//
//

#import <Foundation/Foundation.h>

@interface XMLReader : NSObject <NSXMLParserDelegate>
{
    NSMutableArray *dictionaryStack;
    NSMutableString *textInProgress;
    NSError *errorPointer;
}

+ (NSDictionary *)dictionaryForPath:(NSString *)path error:(NSError **)errorPointer;
+ (NSDictionary *)dictionaryForXMLData:(NSData *)data error:(NSError **)errorPointer;
+ (NSDictionary *)dictionaryForXMLString:(NSString *)string error:(NSError **)errorPointer;

@end

XMLReader.m

//
//  XMLReader.m
//

#import "XMLReader.h"

//NSString *const kXMLReaderTextNodeKey = @"text";

@interface XMLReader (Internal)

- (id)initWithError:(NSError **)error;
- (NSDictionary *)objectWithData:(NSData *)data;

@end

@implementation XMLReader

#pragma mark -
#pragma mark Public methods

+ (NSDictionary *)dictionaryForPath:(NSString *)path error:(NSError **)errorPointer
{
    NSString *fullpath = [[NSBundle bundleForClass:self] pathForResource:path ofType:@"xml"];
    NSData *data = [[NSFileManager defaultManager] contentsAtPath:fullpath];
    NSDictionary *rootDictionary = [XMLReader dictionaryForXMLData:data error:errorPointer];

    return rootDictionary;
}

+ (NSDictionary *)dictionaryForXMLData:(NSData *)data error:(NSError **)error
{
    XMLReader *reader = [[XMLReader alloc] initWithError:error];
    NSDictionary *rootDictionary = [reader objectWithData:data];
    [reader release];

    return rootDictionary;
}

+ (NSDictionary *)dictionaryForXMLString:(NSString *)string error:(NSError **)error
{
    NSArray* lines = [string componentsSeparatedByString:@"\n"];
    NSMutableString* strData = [NSMutableString stringWithString:@""];

    for (int i = 0; i < [lines count]; i++)
    {
        [strData appendString:[[lines objectAtIndex:i] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
    }

    NSData *data = [strData dataUsingEncoding:NSUTF8StringEncoding];
    return [XMLReader dictionaryForXMLData:data error:error];
}

#pragma mark -
#pragma mark Parsing

- (id)initWithError:(NSError **)error
{
    if ((self = [super init]))
    {
        errorPointer = *error;
    }

    return self;
}

- (void)dealloc
{
    [dictionaryStack release];
    [textInProgress release];

    [super dealloc];
}

- (NSDictionary *)objectWithData:(NSData *)data
{
    // Clear out any old data
    [dictionaryStack release];
    [textInProgress release];

    dictionaryStack = [[NSMutableArray alloc] init];
    textInProgress = [[NSMutableString alloc] init];

    // Initialize the stack with a fresh dictionary
    [dictionaryStack addObject:[NSMutableDictionary dictionary]];

    // Parse the XML
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
    parser.delegate = self;
    BOOL success = [parser parse];
    [parser release];

    // Return the stack's root dictionary on success
    if (success){
        NSDictionary *resultDict = [dictionaryStack objectAtIndex:0];
        return resultDict;
    }

    return nil;
}

# pragma mark
# pragma mark - NSXMLParserDelegate methods

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    // Get the dictionary for the current level in the stack
    NSMutableDictionary *parentDict = [dictionaryStack lastObject];

    // Create the child dictionary for the new element
    NSMutableDictionary *childDict = [NSMutableDictionary dictionary];

    // Initialize child dictionary with the attributes, prefixed with '@'
    for (NSString *key in attributeDict) {
        [childDict setValue:[attributeDict objectForKey:key]
                     forKey:key];
    }

    // If there's already an item for this key, it means we need to create an array
    id existingValue = [parentDict objectForKey:elementName];

    if (existingValue){
        NSMutableArray *array = nil;

        if ([existingValue isKindOfClass:[NSMutableArray class]]){
            // The array exists, so use it
            array = (NSMutableArray *) existingValue;
        }
        else{
            // Create an array if it doesn't exist
            array = [NSMutableArray array];
            [array addObject:existingValue];

            // Replace the child dictionary with an array of children dictionaries
            [parentDict setObject:array forKey:elementName];
        }

        // Add the new child dictionary to the array
        [array addObject:childDict];
    }
    else{
        // No existing value, so update the dictionary
        [parentDict setObject:childDict forKey:elementName];
    }

    // Update the stack
    [dictionaryStack addObject:childDict];
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    // Update the parent dict with text info
    NSMutableDictionary *dictInProgress = [dictionaryStack lastObject];

    // Pop the current dict
    [dictionaryStack removeLastObject];

    // Set the text property
    if ([textInProgress length] > 0){
        if ([dictInProgress count] > 0){
            [dictInProgress setObject:textInProgress forKey:kXMLReaderTextNodeKey];
        }
        else{
            // Given that there will only ever be a single value in this dictionary, let's replace the dictionary with a simple string.
            NSMutableDictionary *parentDict = [dictionaryStack lastObject];
            id parentObject = [parentDict objectForKey:elementName];

            // Parent is an Array
            if ([parentObject isKindOfClass:[NSArray class]]){
                [parentObject removeLastObject];
                [parentObject addObject:textInProgress];
            }

            // Parent is a Dictionary
            else{
                [parentDict removeObjectForKey:elementName];
                [parentDict setObject:textInProgress forKey:elementName];
            }
        }

        // Reset the text
        [textInProgress release];
        textInProgress = [[NSMutableString alloc] init];
    }

    // If there was no value for the tag, and no attribute, then remove it from the dictionary.
    else if ([dictInProgress count] == 0){
        NSMutableDictionary *parentDict = [dictionaryStack lastObject];
        [parentDict removeObjectForKey:elementName];
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    // Build the text value
    [textInProgress appendString:[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
}

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
    // Set the error pointer to the parser's error object
    if (errorPointer)
        errorPointer = parseError;
}

@end

Use it:

NSMutableDictionary *yourDic= (NSMutableDictionary *)[XMLReader dictionaryForXMLData:yourData error:&error];