Question

In my application I need to send request to server to get xml after particular time interval say 1 hour to get the latest data.I want to perform this activity in background.Can anyone suggest how I can achieve this?

Thanks in advance!

Answer 1

To solve above problem I created NSOperation to send request to server and parse response.Its very useful and better than using thread.

1.I created NSTimer instance which will call -(void)sendRequestToGetData:(NSTimer *)timer after particular time interval as follows:

//Initialize NSTimer to repeat the process after particular time interval...
    NSTimer *timer = [NSTimer timerWithTimeInterval:60.0 target:self selector:@selector(sendRequestToGetData:) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];

2.Then inside sendRequestToGetData I created NSOperation by subclassing NSOperation as follows:

-(void)sendRequestToGetData:(NSTimer *)timer
{
    //Check whether user is online or not...
    if(!([[Reachability sharedReachability] internetConnectionStatus] == NotReachable))
    {
        NSURL *theURL = [NSURL URLWithString:myurl];
        NSOperationQueue *operationQueue = [NSOperationQueue new];
        DataDownloadOperation *operation = [[DataDownloadOperation alloc] initWithURL:theURL];
         [operationQueue addOperation:operation];
         [operation release];
    }
}

Note: DataDownloadOperation is subclass of NSOperation.

//DataDownloadOperation.h

#import <Foundation/Foundation.h>

@interface DataDownloadOperation : NSOperation
{
    NSURL *targetURL;
}
@property(retain) NSURL *targetURL;
- (id)initWithURL:(NSURL*)url;

@end

//DataDownloadOperation.m
#import "DataDownloadOperation.h"
#import "XMLParser.h"

@implementation DataDownloadOperation
@synthesize targetURL;

- (id)initWithURL:(NSURL*)url
{
    if (![super init]) return nil;
    self.targetURL = url;
    return self;
}

- (void)dealloc {
    [targetURL release], targetURL = nil;
    [super dealloc];
}

- (void)main {

    NSData *data = [NSData dataWithContentsOfURL:self.targetURL];
    XMLParser *theXMLParser = [[XMLParser alloc]init];
    NSError *theError = NULL;
    [theXMLParser parseXMLFileWithData:data parseError:&theError];
    NSLog(@"Parse data1111:%@",theXMLParser.mParsedDict);
    [theXMLParser release];
}

@end