How to grab an XML element and store it? Objective C - ios

Question

I am trying to grab a token from a website. Upon successful authentication, an XML document would be displayed.
I created a connection as shown below:
NSString *strURLQueryString = [NSString stringWithFormat:#"%#?username=%#&password=%#", kURL_LOGIN, nameString, passwordString];
NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:strURLQueryString]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
In order to display the output, I used this:
unsigned char byteBuffer[[receivedData length]];
[receivedData getBytes:byteBuffer];
NSLog(#"Output: %s", (char *)byteBuffer);
So some of the output of the returned document is as shown below:
<status>0</status><reason>User fetched.</reason><token>9cb7396dccabe68c067521db219afb83</token>
I have read many XML parsing implementation but I just could not implement it as it does not fulfil my need, and I just could not understand the complexity of its explanation.
Would appreciate if anyone could give me a good advice on how to go about.

Answer 1

- (XMLParserViewController *) initXMLParser {
appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
return self;
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
attributes:(NSDictionary *)attributeDict
{
if([elementName isEqualToString:#"Books"]) {
appDelegate.books = [[NSMutableArray alloc] init];
}
else if([elementName isEqualToString:#"Book"])
{
aBook = [[Books alloc] init];
}
NSLog(#"Processing Element: %#", elementName);
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
if(!currentElementValue)
currentElementValue = [[NSMutableString alloc] initWithString:string];
else
[currentElementValue appendString:string];
NSLog(#"Processing Value: %#", currentElementValue);
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
if([elementName isEqualToString:#"Books"])
return;
if([elementName isEqualToString:#"Book"])
{
[appDelegate.books addObject:aBook];
aBook = nil;
}
else if([elementName isEqualToString:#"name"])
{
aBook.name=currentElementValue;
}
else if([elementName isEqualToString:#"address"])
{
aBook.address=currentElementValue;
}
else if([elementName isEqualToString:#"country"])
{
aBook.country=currentElementValue;
}
currentElementValue = nil;
NSLog(#"%#",aBook.name);
NSLog(#"%#",aBook.address);
NSLog(#"%#",aBook.country);
}
Try this ,, I hope this works....

Answer 2

The relevant NSXMLParserDelegate methods:
-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName //etc
{ _inToken = [elementName isEqualToString:#"token"]; }
-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName //etc
{ _inToken = NO; }
-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
if (_inToken) {
_token = string;
[parser abortParsing];
}
}

Answer 3

You should use XML parser.
It is easy to use, go all below steps to get best result:
Create XMLParser class subclasses from NSXMLParser, so you have a NSXMLParser.h and NSXMLParser.m class
your .h class must be like this:
#import <Foundation/Foundation.h>
#interface XMLParser : NSXMLParser <NSXMLParserDelegate>{
NSUInteger parsedCounter;
BOOL accumulatingParsedCharacterData;
BOOL didAbortParsing;
}
#property (nonatomic, strong) NSMutableString *currentParsedCharacterData;
#property (nonatomic, strong) NSMutableArray *currentParsedCharacterArray;
#end
And .m class :
#import "XMLParser.h"
#implementation XMLParser
#pragma mark Parser constants
// Limit the number of parsed data to 100.
static const NSUInteger kMaximumNumberOfFilesToParse = 100;
static NSUInteger const kSizeOfFileBatch = 10;
// Reduce potential parsing errors by using string constants declared in a single place.
static NSString * const kEntryElementName = #"dlResult";
static NSString * const kStringElementName = #"string";
#pragma mark NSXMLParser delegate methods
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
// NSLog(#"didStart");
// If the number of parsed earthquakes is greater than kMaximumNumberOfEarthquakesToParse, abort the parse.
if (parsedCounter >= kMaximumNumberOfFilesToParse) {
// Use the flag didAbortParsing to distinguish between this deliberate stop and other parser errors.
didAbortParsing = YES;
[self abortParsing];
}
if ([elementName isEqualToString:kEntryElementName]) {
_currentParsedCharacterArray = [[NSMutableArray alloc]init];
} else if ([elementName isEqualToString:kStringElementName]) {
accumulatingParsedCharacterData = YES;
_currentParsedCharacterData = [[NSMutableString alloc]init];
}
}
// return string between tags
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
// NSLog(#"foundCh");
if (accumulatingParsedCharacterData) {
// If the current element is one whose content we care about, append 'string'
// to the property that holds the content of the current element.
[_currentParsedCharacterData appendString:string];
NSLog(#"currentParsedCharacterData:%#",_currentParsedCharacterData);
}
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
// NSLog(#"didEnd");
if ([elementName isEqualToString:kStringElementName]) {
[_currentParsedCharacterArray addObject:_currentParsedCharacterData];
}
accumulatingParsedCharacterData = NO;
}
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
if (didAbortParsing == NO) {
// Pass the error to the main thread for handling.
[self performSelectorOnMainThread:#selector(handleError:) withObject:parseError waitUntilDone:NO];
}
}
#end
In .m class there are two const string:
static NSString * const kEntryElementName = #"dlResult";
static NSString * const kStringElementName = #"string";
those are string tags,the tags that you should implement are "status", "reason" "token"
from connection class, send data connection to XMLParser class like below:
#autoreleasepool {
// It's also possible to have NSXMLParser download the data, by passing it a URL, but this is not desirable
// because it gives less control over the network, particularly in responding to connection errors.
//
XMLParser *parser = [[XMLParser alloc] initWithData:data];
parser.currentParsedCharacterArray = [NSMutableArray array];
parser.currentParsedCharacterData = [NSMutableString string];
[parser setDelegate:parser];
[parser parse];
// depending on the total number of earthquakes parsed, the last batch might not have been a "full" batch, and thus
// not been part of the regular batch transfer. So, we check the count of the array and, if necessary, send it to the main thread.
if ([parser.currentParsedCharacterArray count] > 0) {
// send parsed data to another class or ...
// parser.currentParsedCharacterArray is parsed data
}
parser.currentParsedCharacterArray = nil;
parser.currentParsedCharacterData = nil;
}
if you have any question, ask me!